Previous investigations of the variable marking of past time by the L2 learner have given rise to a number of hypotheses which predict the patterns of acquisition and use of past time markers in interlanguage (IL). However, given the complicity between their predictions, it has been previously noted that hypotheses such as the aspect and discourse hypotheses can be supported with the same data. In an attempt to distinguish between the effects of such multiple constraints in advanced French IL, this paper presents quantitative findings to suggest that no single factor exclusively outweighs another, but rather, the factors "interact" in their effect, such that the causes of aspectuo-temporal variation are not singular, but indeed multiple. (Contains 3 tables and 15 notes.)