An experiment was conducted to investigate the relationship between the locus of control orientation of fourth-grade children and delay frustration experienced in self-imposed and externally imposed delay situations. Time estimation was used as the index of delay frustration, with greater time estimates being interpreted as indicating greater frustration. In a self-imposed delay situation, external subjects estimated a 5-min delay to be longer than did internal subjects, while in an externally imposed delay situation, internal subjects estimated a 5-min delay to be longer than did external subjects. The implications of the findings for an understanding of both the locus of control dimension and delay behavior are discussed.