People make personal plans regarding whether, when, where, and how to undertake certain actions. We discuss three questions related to personal plans. First, what are the effects of plans on behavior? Second, when are plans formed? Third, how do plans deviate from optimality? For each of these questions, we (a) offer a brief overview of research that sheds light on the issue and (b) identify gaps in current knowledge. We emphasize connections to the growing theoretical literature that gives personal plans a substantive role, but we conclude that more research is needed, especially on the latter two questions we cover.

Using a field experiment in a 401(k) plan, we measure the effect of disseminating information about peer behavior on savings. Low‐saving employees received simplified plan enrollment or contribution increase forms. A randomized subset of forms stated the fraction of age‐matched coworkers participating in the plan or age‐matched participants contributing at least 6% of pay to the plan. We document an oppositional reaction: the presence of peer information decreased the savings of nonparticipants who were ineligible for 401(k) automatic enrollment, and higher observed peer savings rates also decreased savings. Discouragement from upward social comparisons seems to drive this reaction.