A study of the effects of the complexity of scenarios used in the Strategic Interaction Method of second language instruction had four scenarios of varying complexity performed by four university classes of students of English as a second language at varying levels. Indicators of complexity included the degree of verbalness, contextual constraint, formulaic language required, amount of grammar or artifact required to resolve the situation, and the amount of vocabulary or technical terminology needed. The measures used were mean length of utterance and verbal and nonverbal communication strategies used in the scenario performances. It is concluded that the complexity of the scenarios is important in the language learning process. Less complex scenarios promote more effective learning at lower levels, and more complex scenarios promote more effective interaction at higher levels. (MSE)