Agreeableness is linked to socially valued traits and prosocial motives, so self-reported Agreeableness may be distorted by self-favoring biases (SFB). A three-study multimethod research program explored links between the Big Five dimension of Agreeableness and SFB from three perspectives. First, we examined zero-order relations between Agreeableness and SFB measures (N = 316). Next, we used a round robin design (N = 351) and the Social Relations Model analyses (Kenny, 1994) to partition perceptions of Agreeableness into target and perceiver effects. These effects then were related to SFB concerns, and differential responsiveness to a manipulation of the social desirability of Agreeableness. Study 3 (N = 312) examined a manipulation of Agreeableness as a moderator of the relation between dispositional Agreeableness and interpersonal conflict tactics. Overall, results indicate that Agreeableness is not easily manipulated nor distorted by SFB. Results are discussed in terms of Agreeableness as a substantive system of motives.