Why do similar households end up with very different levels of wealth? We show that differences in the attitudes and skills with which they approach finan-cial planning are a significant factor. We use new and unique survey data to assess these differences and to measure each household’s “propensity to plan. ” We show that those with a higher such propensity spend more time developing financial plans, and that this shift in planning is associated with increased wealth. These findings are consistent with broad psychological evidence concern-ing the beneficial impacts of planning on goal pursuit. Those with a high propen-sity to plan may be better able to control their spending, and thereby achieve their goal of wealth accumulation. We find direct evidence supporting this effortful self-control channel in the very strong relationship we uncover between the propensity to plan and budgeting behavior. I.