Over 10 years of research has illustrated the benefits of internal motivation to respond without prejudice (IMS) for prejudice regulation and high-quality intergroup contact (see Plant & Devine, 1998). Yet, it is unclear how this motivation develops. The current work tested one route through which feelings of acceptance from outgroup members facilitate the development of IMS. Longitudinally, feeling accepted by outgroup members predicted increases in IMS across a 15-week period (Study 1). Experimental manipulations of outgroup acceptance also increased IMS toward racial outgroups (Studies 2 and 3). Furthermore, IMS mediated the relationship between outgroup acceptance and participants’ increased willingness to pay money to increase opportunities for interracial contact (Study 2). Tests of mediation also demonstrated that feelings of acceptance mediated the effect of outgroup acceptance on internal motivation (Study 3). In addition, this pattern of responses held for members of both high- and low-status racial groups. This research demonstrates one pathway through which the fulfillment of fundamental needs influences motivated intergroup processes.