Given that this special issue is devoted to the acquisition and processing of inflectional morphology by second language (L2) learners, the question in the title may appear redundant. However, recent research on first language (L1) and L2 morphological processing has challenged basic assumptions about the status of inflectional morphology in linguistic processing that had long been taken for granted. This issue demonstrates how experimental paradigms and theoretical positions developed in L1 and L2 research result in a new synergy and advance one's understanding of the complex mechanisms implicated in morphological processing. The goal of this paper is to briefly review the main theoretical positions vis-a-vis inflectional morphology and to identify points of convergence between research on L1 and L2 morphological processing. Three points are relevant for the issue's agenda. First, debates between the extreme positions expressed by the dual-system and single-system approaches to inflectional morphology, which hinge on a categorical distinction between regular and irregular inflection and a no less categorical interpretation of the role of frequency, have highlighted the strengths and weaknesses in both approaches. Apparently, more often than not, there is a continuum between regular and irregular processing. Second, crosslinguistic comparisons signal significant differences in the processing of inflection among languages ranging in morphological richness. Third, and crucially for this research, the discussions of purely SLA-driven issues in morphological processing, such as differences in early and late L2 learning, the role of L1 background, and the relative distance between L1 and L2, as well as the type of input received by L2 learners, are moving to the forefront. (Contains 12 notes.)