The purpose of this study was to develop a method for assessing young children's perceptions of classroom friendships and to determine whether these perceptions were associated with their adjustment during the transition to grade school. Subscales tapping 5 friendship processes (e.g., validation, aid, disclosure of negative affect, exclusivity, conflict) were extracted from a 24-item friendship interview that was individually administered to 82 kindergarten children (M age = 5.61) who possessed a reciprocated and stable "best" friend in their classroom. Children's reports of the investigated friendship processes were found to be reliable, and processes such as perceived validation and conflict predicted children's satisfaction with their friendships, and the stability of these relationships. Perceived conflict in friendships was associated with multiple forms of school maladjustment for boys, including higher levels of school loneliness and avoidance and lower levels of school liking and engagement. For both boys and girls, validation and aid forecasted gains in perceived support from classmates, and aid also predicted improvements in children's school attitudes. Perceived exclusivity in friendships was associated with lower levels of achievement. These findings, and others reported in this article, are consistent with the hypothesis that the relational features of children's classroom friendships yield psychological benefits or costs (e.g., provisions) that, in turn, affect their development and adjustment.