This article examines the conditions under which partisan identities shape the positions people express on four political values: equal opportunity, self-reliance, moral traditionalism, and moral tolerance. The theoretical framework posits that (1) party source cues activate latent partisan biases in the minds of citizens, which in turn affect the degree to which individuals express support for these values; (2) out-party cues are more powerful motivators of value expression than in-party cues; (3) value shifts are more pronounced when liberal-conservative identities reinforce partisan sentiments; and (4) partisan cues promote horizontal constraint among these values. These hypotheses are tested using data from a set of experiments appearing on a novel national survey. The empirical results generally support these theoretical expectations.