Retirement planning is a widely promoted activity to enhance wellbeing for aging populations. However, there is limited follow-up data to understand the antecedents of multi-dimensional retirement planning activities, the resources such activities produce or the explanatory mechanisms. This research draws on recent theorizing, which suggests that retirement planning may play a mediating role in explaining how pre-retirement antecedents are transformed into retirement resources. Antecedents, planning and retirement resources were examined using 3 waves of follow-up data collected in 2006, 2008, and 2014. Four hundred thirty-five people originally employed in 2008 and retired by 2014 participated in the study. Health, income, and a positive retirement attitude (T1) were the strongest predictors of retirement planning (T2), but job satisfaction and occupation also played smaller predictive roles. Financial planning (T2) predicted health, psychosocial, and financial resources in retirement (T3). However, health, lifestyle, and psychosocial planning played a minimal role in explaining retirement resources, and only financial planning demonstrated noteworthy evidence of mediation. Findings can help to inform policy decisions by identifying those at greatest risk of not planning, and to isolate the factors most likely to explain the longer-term effects of planning. Understanding which resources are predicted by different domains of planning will also help inform the targeting of interventions.