This guide is intended to help teachers plan, design, and implement science activities for students learning English as a Second Language (ESL) in grades 4-8, in mainstream science classes, ESL classes, bilingual education programs, and also to help others serving this population. Steps for designing science experiments that integrate language and science content effectively are presented. The activities included have been used successfully with this group. Principles of learning and teaching proposed by the American Association for the Advancement of Science are enumerated and explained, and specific strategies for integrating language and science are outlined, including teacher collaboration, student collaboration, modifying language for clarity, using material that is meaningful to students, adapting science materials for student language proficiency levels, using language teaching techniques, and varying instructional strategies according to student proficiency. A discussion of the design of science activities for ESL students offers a model procedure in which science concepts are examined through three activity types: teacher demonstration, then group investigation, and finally, individual investigation. Appropriate science concepts and language functions are discussed. Sample activities on heat, animals, and plants using this procedure are outlined in detail. A 24-item bibliography is included. (MSE)