The present study investigated the relative contributions of experiential and ability factors to second language (L2) passage comprehension and L2 vocabulary retention. Participants included a cross section of 99 adult learners of Spanish as a foreign language enrolled in beginning through advanced level university Spanish courses. Participants completed a standardized reading proficiency test (Adult Basic Learning Examination, Spanish version) to verify a range in proficiency, a checklist and translation "passage sight vocabulary" test, and a written recall in the native language of the 4 passages that were read. Vocabulary retention was measured at 2 time intervals by a multiple-choice test of receptive retention of meaning of targeted vocabulary. Data were analyzed using structural equation modeling (SEM). Results revealed consistent support for the following model: (a) Language processing experience positively influenced L2 passage sight vocabulary; (b) L2 passage sight vocabulary positively influenced narrative passage comprehension; and (c) L2 comprehension positively influenced L2 vocabulary growth. (Contains 5 tables, 3 figures, and 5 notes.)