With the purpose of highlighting the lessons to be learned from immersion programs, this digest presents selected findings from research carried out to evaluate the effectiveness of immersion programs in Canada and the United States. These lessons are related to the importance of: (1) integrating language with content instruction (when second language instruction is integrated with instruction in academic content, it is more effective than teaching the language in isolation); (2) creating classroom environments that are discourse-rich (providing opportunities for extended student discourse, especially discourse associated with activities selected by individual students, can be particularly beneficial for second language learning); and (3) systematically planning language instruction along with content instruction. (Contains seven references.) (JL)