This study examines the effects of education and input as predictors of adult second language acquisition in naturalistic contexts. L1 Albanian learners of Greek who differed in amount of schooling (from 4 to 16 years) and length of residence (from 8 to 27 years) completed elicitation tasks that tested mastery of gender and number agreement, and past tense morphology. In addition, samples of spontaneous speech were assessed for fluency, grammatical complexity, and lexical richness in order to establish the learners’ overall proficiency in the L2. We hypothesized that education would facilitate attention to form and hence lead to better attainment of grammatical distinctions with relatively low functional load, particularly when these are complex. Quantity of input would be most strongly associated with aspects of language that are most relevant to communication, and in particular, fluency. These predictions were largely confirmed: education accounted for 15% of the variance on adjective number agreement and between 31% and 38% of the variance in performance on past tense morphology, which is considerably more complex. Fluency and clausal density, in contrast, were associated with length of residence but not with education.