Nick Ellis's article is impressive for its breadth of scholarship and the cogent case made for frequency as an important factor in second language acquisition (SLA). This response begins with a brief historical sketch, which aims to contextualize the frequency factor in terms of the evolution of SLA research. Although researchers have known about a frequency effect for some time, until recently, we have lacked neurologically plausible models and technologically convenient means of measuring and testing frequency effects in input. Still, as relevant and important as a frequency factor is, it requires greater definition and qualification. For instance, L2 learners are agents of their own learning process. They do not merely record frequency; they categorize frequently occurring patterns, abstract, and generalize from them. Higher level generalizations emerge from interactions, impose top-down expectancies on future data, and, in turn, are altered by the data in a perpetually dynamic interplay. In a similar fashion, it is incumbent on SLA researchers not to be satisfied with a frequency explanation, but to interpret it—in short, to make sense of frequency.