Institutional theorists have made major progress in recent years examining gradual processes of endogenous institutional change. Building on this line of theorizing, this article highlights an often overlooked source of incremental change in political institutions: investments in institutional resources. Unlike path-dependent processes, which are relatively open at the front end and relatively closed at the back end, resource investments made in one period serve to widen an institution's path and enhance its capacity to undertake a broader range of activities in subsequent periods. Drawn out over time, these investments can gradually transform institutional operations and purposes. To illustrate these dynamics, this article reconsiders the transformation of the national party committees into “parties in service” to their candidates. The most influential theoretical explanation for this change is supplied by actor-centered functionalist accounts that either ignore the parties' institutional forms or treat them as mere reflections of actors' preferences. As an alternative, I suggest that investments in two types of institutional resources—human resources and information assets—were integral to the process through which each party changed. Piecemeal investments in these resources gradually enabled each national party committee to provide a wider range of campaign services to its candidates, thereby producing ostensibly new “functions” over time. Though the process of institutional change unfolded at very different times in each party, the same dynamics were on display in both cases.