This study examined the componential structure of second-language (L2) speaking proficiency. Participants--181 L2 and 54 native speakers of Dutch--performed eight speaking tasks and six tasks tapping nine linguistic skills. Performance in the speaking tasks was rated on functional adequacy by a panel of judges and formed the dependent variable in subsequent analyses (structural equation modeling). The following independent variables were assessed separately: linguistic knowledge in two tests (vocabulary and grammar); linguistic processing skills (four reaction time measures obtained in three tasks: picture naming, delayed picture naming, and sentence building); and pronunciation skills (speech sounds, word stress, and intonation). All linguistic skills, with the exception of two articulation measures in the delayed picture naming task, were significantly and substantially related to functional adequacy of speaking, explaining 76% of the variance. This provides substantial evidence for a componential view of L2 speaking proficiency that consists of language-knowledge and language-processing components. The componential structure of speaking proficiency was almost identical for the 40% of participants at the lower and the 40% of participants at the higher end of the functional adequacy distribution (n = 73 each), which does not support Higgs and Clifford's (1982) relative contribution model, predicting that, although L2 learners become more proficient over time, the relative weight of component skills may change.