Various explanations have been put forth for the asymmetrical acquisition of tense and aspect morphology across categories of lexical aspect. This experiment tested the adequacy of a subset of such accounts by examining English native speakers' (n = 40) use of progressive and past tense morphology within activity and accomplishment verb frames during their early acquisition of a miniature artificial language. Participants completed a lesson in which types and tokens of lexical aspect and past and present morphology were balanced. Although significant effects at p < 0.05 were found for lexical aspect and morphological marking, the interaction between these factors, expected by the aspect hypothesis, was non-significant. The experiment suggests that the effects of lexical aspect may be absent during the earliest phases of second language acquisition or may be due to factors methodologically excluded in this study such as distributional biases in second language input.