Learning inflectional morphology is a vexing problem for second language (L2) learners. Children acquiring their native language also experience some difficulty, which results in their committing overgeneralization errors. Long after individuals have achieved a high level of proficiency in the L2, they are still plagued by uncertainty when it comes to grammatical inflections, and their production in the L2 is still characterized by morphological omissions, commissions, and substitutions of one allomorph for another. Because of the combination of these two factors--acquisition difficulty and relative ease of studying it--the acquisition and processing of grammatical morphology has long been of focal interest to researchers. In fact, some would point to the morpheme acquisition studies of the 1970s as instrumental in the establishment of second language acquisition (SLA) as an autonomous field of study. In this commentary, the author begins by observing that the field of SLA got its start in morpheme acquisition. The author realizes that the acquisition of morphemes was just one small part of a complex picture. The author contends that people are susceptible to falling into the same trap again by using the acquisition of morphology to decide between a rule-based or associative learning account of SLA. To ward off premature closure, the author argues that it would be better if people adopt more modest aspirations for now and turn their attention to careful longitudinal studies of morphological development of many different types of learners speaking many different types of L1s and learning many different types of L2s in many different contexts and learning situations.