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Thought and Second Language: A Vygotskian Framework for Understanding BICS and CALP

By James Bylund

Language diversity has been a defining characteristic of U.S. public schools throughout their history, and this phenomenon shows no signs of slowing down. Over the 10 year period between 1994–1995 and 2004–2005, the number of students in U.S. public schools classified as limited English proficient (LEP) grew from roughly 3.2 to 5.1 million, an increase of 57% (National Clearinghouse for English Language Acquisition, 2006). Public schools are responsible for educating students from diverse linguistic backgrounds, and efforts to do so have often involved immersing these students in English-only programs at the expense of their primary language.

Rhodes, Ochoa, and Ortiz (2005) point out the common misconception held by many in the general public, including the parents of second language learners and school personnel, that bilingual education may adversely affect a student’s English language development. The authors refer to this phenomenon as the “immersion myth” (Rhodes, et al., 2005, p. 58). Unfortunately, the immersion myth has lead to placement decisions that have not produced desired educational outcomes. As a group, LEP students are performing far below their monolingual English speaking peers across numerous indicators including standardized test performance, retention rates, and the number of students dropping out of school (Rhodes et al., 2005).

Across the country, second language learners are participating in English-only programs, pullout English as a second language (ESL) instruction, content-based ESL, transitional bilingual programs, maintenance bilingual programs, and dual language bilingual programs (Ochoa & Rhodes, 2005). Even though a wide range of different programs is currently in place, the long-term outcomes for students in these programs vastly differ. Rhodes et al. (2005) cite research conducted by Thomas and Collier in illustrating the fact that LEP students initially make similar gains in English language reading development regardless of the type of language instruction they receive (e.g., ESL pullout or two-way bilingual education). However, this pattern is short lived. The short-term gains experienced by students in transitional and ESL programs begin to level off, or even disappear over time, while students in maintenance bilingual education programs continue to progress in their English language reading skills well into their high school careers, eliminating the achievement gap between their monolingual English speaking peers and themselves. In fact, primary language instruction for 4 or more years has a positive impact on academic achievement that may mitigate the risk of low socioeconomic status faced by many language minority students (Thomas & Collier, 2002).


Clearly, these studies demonstrate the positive long-term impact of primary language instruction on the development of students’ English language academic skills. But how could this be? How could instruction in Spanish, for example, benefit a student’s English literacy development? To answer this question, researchers often point to the work of Cummins (1981), who proposed that two distinct types of language proficiency exist, basic interpersonal communications skills (BICS) and cognitive/academic language proficiency (CALP). BICS includes aspects of language such as basic vocabulary and pronunciation, skills that are readily apparent during conversations between two or more people. Often, this type of interpersonal communication depends on the context in which the conversation takes place, since meanings of words are related to “situational and paralinguistic clues” (Cummins, 1981, p. 23). In contrast, CALP refers to language skills that allow an individual to process and make meaning of language that exists independent of any situational clues, and is the language skill required for meaningful engagement in most academic tasks. LEP students’ command of BICS is often misleading in that they may possess surface level language skills and be able to carry on a conversation in English, yet lack the CALP skills necessary for success in academic settings.

Cummins (1981) proposed that the best way for a student to develop CALP in their second language was to first develop CALP in their primary language. In fact, students may not be able to develop second-language CALP until they have first reached some minimum threshold in their primary language (Rhodes et al., 2005). According to Cummins, an individual’s mastery of his/her primary language (L1) supports the development of a second language (L2) because of common underlying features across languages such as the ability to generate meaning from disembedded words and phrases. Consistent with Cummins’ theory, Thomas and Collier (2002) asserted that the strongest predictor of L2 achievement is the amount of L1 schooling (i.e., the more L1 grade level schooling, the higher L2 achievement).

Vygotsky’s Theory of Thought and Language

While Cummins made invaluable contributions to our understanding of second language development and the need for bilingual education, his theory of BICS and CALP is largely descriptive and does not explain the underlying cognitive processes involved in second language development. Vygotsky (1986/1934), writing more than 45 years before Cummins, provides theoretical insight into this process. The acclaimed Russian developmental psychologist describes the use of language as a psychological tool for the purpose of analyzing and solving complex problems. Problem-solving ability, a stage in language development that Vygotsky refers to as “the use of concepts,” is essentially the equivalent of Cummins’ CALP.

As educators, we often focus our attention on the external features of language such as pronunciation, fluency, and grammar (i.e., BICS), while overlooking the role that language plays in complex thought processes. According to Vygotsky (1986/1934), language development unfolds along a continuum, beginning with disorganized assignment of symbols (words) to various objects, and culminating in a final stage of mature conceptual thinking. He used the terms “inner speech” and “verbal thought” to refer to our use of language as a psychological tool when engaging in higher-level cognitive activities. This use of language is a uniquely human capacity that allows us to move beyond our immediate experience and form relationships among pieces of information, to establish patterns, and make predictions.

Cummins attributed the transfer of CALP in L1 to CALP in L2 to a common underlying proficiency (CUP). However, for CALP skills to transfer between languages that differ in terms of their external characteristics, the essence of that which is transferred must be related to, but separate from, the languages themselves. Vygotsky’s work suggests that the transferred information involves the use of mature concepts as part of one’s “verbal thought.” This represents the final stage of language development at which time we use concepts as cognitive tools for creating meaning from our experiences. This final stage is not language per se, but the intersection of thought and language. According to Vygotsky (1986/1934), “verbal thought” facilitates complex thought processes by selecting, organizing, and imprinting essential pieces of information, as well as exploring multiple meanings within subordinate and superordinate categories.

Students who lack the necessary concepts will not be able to comprehend certain pieces of information even though they may have knowledge of individual words. Vygotsky (1986/1934) proposed that a concept was not a static formation, but a dynamic entity that both influences thought processes and is influenced by the process of thinking. Thus, a child’s ability to use verbal thought as a cognitive tool develops as s/he accumulates a widening range of word meanings and forms a framework or structure connecting the concepts represented by those words. This involves a semantic map that allows the child to transcend immediate experience by making associations that transform information into entirely new ideas.

Even though thought and language are inextricably linked, Vygotsky (1986/1934) proposed that they develop along separate paths. He proposed that they eventually intersect, as the development of one promotes the development of the other. Thus, the use of concepts as part of verbal thought is not a quantitative extension of one’s accumulation of individual words, but a qualitative change in the way the child uses language to think about information. From a Vygotskian perspective, CALP is more than a simple developmental extension of BICS. CALP is a qualitatively different use of language from that represented by BICS. CALP is not simply language, but the intersection of thought and language.

While children begin to use words early in their development, their understanding and use of concepts occur later. Vygotsky (1986/1934) found that a major shift in the use of verbal concepts for the purpose of abstract reasoning occurred during adolescence. This shift is dependent upon two converging factors. First, Vygotsky (1986/1934) found that approximately prior to age 12, a child’s cognitive functioning is not capable of using abstract concepts to transcend beyond immediate experience. Second, over the course of language development, words take on increasingly differentiated meanings and associations, and it is not until adolescence that children develop a vocabulary sufficiently rich to create an intricate semantic map. Interestingly, the point at which language development and cognitive development intersect corresponds with Cummins’ (1981) findings that, beginning in kindergarten or 1st grade, the development of CALP requires 5–7 years of formal schooling in a language the child comprehends. In such cases, these students would be roughly 11 to 13 years of age.

When comparing the development of speech and intellect with the development of verbal thought, Vygotsky (1986/1934) concluded that verbal thought is not a natural outcome of early speech and intellectual development. In fact, he concluded that, while speech and intellect have a biological genesis, sociocultural processes play a major role in the development of children’s thought and self-regulation. Schools are our cultural institutions assigned with the explicit responsibility of developing children’s thought processes. In young children, the transfer of already-formed concepts to new situations does not occur automatically. When a young child’s language development is disrupted without the direct and intentional effort of adults to create a structure linking what s/he already knows (L1) with what is being learned (L2), conceptual disorganization of word meaning may occur. According to Vygotsky, this may have tragic implications for the development of the child’s thought processes.

There are several untoward consequences of placing LEP students into classes that are taught only in English. First, these children are disconnected from the verbal knowledge they bring with them to school, thereby stifling the development of their primary language skills. Second, while these students begin to accumulate knowledge of their second language, they are doing so years behind their monolingual English speaking peers and are, therefore, unable to access the curriculum in the same manner.

When fully developed, a student’s primary language can provide an established and organized system of meaning that can be applied to new learning situations. These new situations include those in which information is presented in a second language that the student is learning. In other words, an individual can use concepts that are already well developed in their primary language to facilitate learning and problem solving in their second language. In turn, learning a second language serves to simultaneously promote further learning and concept formation in the primary language. As Vygotsky (1986/1934) noted:

[S]uccess in learning a foreign language is contingent on a certain degree of maturity in the native language. The child can transfer to the new language the system of meanings he already possesses in his own. The reverse is also true—a foreign language facilitates mastering the higher forms of the native language. The child learns to see his language as one particular system among many, to view its phenomena under more general categories, and this leads to awareness of his linguistic operations (pp. 195–196).


When working with students who are learning English as a second language, we often focus our attention on the external features of language such as pronunciation, fluency, and grammar while overlooking the role of language as a cognitive tool used in complex thought processes. The use of language as a cognitive tool allows us to move beyond our immediate perceptual experience to engage in abstract thinking and novel problem solving. We use verbal thought to direct our attention, set goals, determine strategies, explore multiple meanings, make inferences, and draw conclusions.

In contrast to words, concepts make up an organized structure of relationships and generalities. The ability to think in terms of concepts, therefore, allows us to transcend our immediate experience to explore past, future, and hypothetical situations. If the young child receives instruction in a language they have yet to master without intentional effort to build transfer between L1 and L2, their development of organized conceptual structures may be disrupted. Clearly, the genesis of such problems does not reside within the child but results from the interaction between the child and the educational system.

While numerous types of programs are available to second language learners throughout the country, only maintenance bilingual and dual immersion bilingual programs have been proven successful in closing the achievement gap between LEP students and their monolingual peers. Other programs such as ESL and transitional bilingual classes may produce initial gains in English language skills, but these early gains do not lead to sustainable long-term improvements in academic performance. Such programs promote the development of BICS, the surface level language skills, while failing to develop the CALP skills (i.e., the semantic map necessary for success in academic settings).


Cummins, J. (1981). Empirical and theoretical underpinnings of bilingual education. Journal of Education. 163, 16–30.

National Clearinghouse for English Language Acquisition. (2006). The growing numbers of LEP students. Retrieved June 8, 2010, from http://www.ncela.gwu.edu/files/uploads/4/GrowingLEP_0506.pdf

Ochoa, S. H., & Rhodes, R. L. (2005). Assisting parents of bilingual students to achieve equity in public school. Journal of Educational & Psychological Consultation. 16, 75–94.

Rhodes, R. L, Ochoa, S. H., & Ortiz, S. O. (2005). Assessing culturally and linguistically diverse students: A practical guide. New York: Guilford Press.

Thomas, W. P., & Collier, V. P. (2002). A national study of school effectiveness for language minority students’ long-term academic achievement: Executive summary. Santa Cruz, CA: Center for Research on Education, Diversity, and Excellence. Retrieved June 8, 2010, from http://www.usc.edu/dept/education/CMMR/CollierThomasExReport.pdf

Vygotsky, L. S. (1986). Thought and language. Cambridge, MA: MIT Press (Original work published 1934).

James Bylund, NCSP, is a school psychologist with the San Diego Unified School District, CA.