Findings from a 4-year study of exemplary science and mathematics programs for middle school students with limited English proficiency (LEP) are presented. The four programs described here provide stimulating mathematics and science curricula through instruction in either the students' native language or in English using sheltered techniques. Common program characteristics include these: (1) all were manifestations of larger national and state-level efforts to improve mathematics and science instruction; (2) the exemplary science and mathematics programs took place in a broader context of school restructuring; and (3) well-conceived and well-implemented language development programs for LEP students were crucial to program success, and included qualified faculty, multiple-program pathways for transition to English, and support for transitioning students to all-English instruction. Contains seven references. (MSE)