Almost universally, research and practice suggest that a brand that increases its product assortment, or variety, should benefit through increased market share. In this paper, we show this is not always the case. We introduce the construct “assortment type” and demonstrate that the effect of assortment size on brand share is systematically moderated by assortment type. We define an “alignable” assortment as a set of brand variants that differ along a single, compensatory dimension such that choosing from that assortment only requires within-attribute trade-offs. In contrast, we define a “nonalignable” assortment as a set of brand variants that simultaneously vary along multiple, noncompensatory dimensions, demanding between-attribute trade-offs. In turn, we argue that an alignable assortment can efficiently meet the diverse tastes of consumers, thereby increasing brand share, but that a nonalignable assortment increases both the cognitive effort and the potential for regret faced by a consumer, thereby decreasing brand share. We term this effect “overchoice.” Across three studies, we provide evidence of overchoice and tie the effect to the effort and regret brought about by nonalignability. In the process, we demonstrate that simplification of information presentation, reversibility of choice, and a reduction in underlying nonalignability serve to reduce or eliminate this effect.