Detailed materials for the assessment of language use in a responsive environment are provided for teachers and teaching assistants. Part A consists of a manual and guide for language assessment. A brief account of the responsive model's approach to language instruction is given. Additional sections introduce and describe the observation and assessment instrument (OAI), and provide guides for its use and scoring. Part B presents the OAI: an instrument which focuses on several kinds of classroom language used to instruct, indicate resources, and give choices. For each category of language use, assessment criteria are listed and a rationale is offered. Scoring scales for preschool and primary school aged children are included. Part C provides a language assessment questionnaire for teachers and teaching assistants. How the OAI can be used for self assessment by teachers and teaching assistants is indicated in Part D. (Author/RH)