The process of designing and validating a test of English-as-a-Second-Language (ESL) speaking skills is described. The study examined: (1) whether nine traits (pronunciation, grammar, discourse, fluency, content, vocabulary, comprehensibility, interactional competence, sociolinguistic competence) are relevant and separable parts of speaking ability; (2) whether there is a relationship between test methods and language ability; (3) whether the traits are fundamental elements of ability; and (4) how the traits are related. Three testing methods were compared: a written test; an interview test; and a tape-mediated speaking test. Results indicate that three factors obtained through factor analysis correspond to three methods for measuring ability: written communication ability; direct oral communication ability; and semi-direct oral communication ability. The traits appear to work differently within each ability. Implications are drawn for teaching and for further testing research. (Contains 19 references.) (MSE)