A study of the affective "filter" inhibiting student learning of a second language focuses on the critical features of the filter, especially student self-concept and the general roles of personality traits and learning attitudes. Relevant research on motivation, personality traits, attitudes, and self-concept as they relate to learning is reviewed and three learning models are discussed: the motivational model, the "filter" model, and the self-concept model. Specific aspects of motivation, personality traits, attitudes, and self-concept that may relate to language learning are outlined and applied to existing research findings. In conclusion, a working hypothesis concerning the affective filter in language learning, to be validated in a later study, is proposed. A seven-page reference list is provided and figures for the three learning models are appended. (MSE)