Research on second language (L2) grammar in task-based language learning has yielded inconsistent results regarding the effects of task-complexity, prompting calls for more nuanced analyses of L2 development and task performance. The present cross-sectional study contributes to this discussion by comparing the performance of 245 learners of German at two universities in the USA on two types of assessment tasks using multidimensional analyses of grammatical accuracy, fluency and complexity. Results show that: (1) grammatical accuracy in learner performance did not improve linearly across two years of instruction in either task condition; (2) participants tended to perform more accurately in the integrative task than on discrete-point items; (3) second-year learners wrote more fluently than first-year learners; and (4) fourth-semester learners wrote more complex sentences than other groups. The results yield important research, pedagogical and curricular insights.