This document discusses the difference between basic interpersonal communication skills (BICS) and cognitive academic language proficiency (CALP) as defined by Jim Cummins in 1979. BICS refers to conversational fluency in a language, while CALP refers to academic proficiency, including listening, speaking, reading, and writing skills for an educational setting. The document notes that it can take 2-3 years to develop BICS but 5-7 years or more to develop CALP. It emphasizes that students' language abilities should not be assessed based only on BICS and that teachers need to support the development of both BICS and CALP.