This cross-sectional study investigates task variability focusing on the use of Spanish past tense morphology in a spoken learner corpus. Sixty L2 learners of Spanish (English L1) from three different proficiency levels (20 per group) and fifteen native speakers completed three communicative tasks (a guided interview, a picture-based narrative, and a historical figures description) and an experimental task, all designed to investigate the acquisition of tense and aspect in L2 Spanish. Data were transcribed in CHAT, and analysed and coded using a specially created interactive coding program that works in combination with the CLAN program (MacWhinney 2000). Results demonstrate significant differences in the emergence and accurate use of past tense morphology across tasks. An additional analysis showed that the less controlled tasks encouraged few instances of more advanced features, suggesting that not all task types are equally successful at eliciting the range of tense-aspect morphological contrasts theoretically relevant for SLA research on tense and aspect.