A number of theorists have maintained that cognitive events such as irrational beliefs mediate various affective and behavioral disorders. Jones' (1968) Irrational Beliefs Test (IBT) is a prominent self‐report instrument that assesses dispositional rationality‐irrationality with respect to 10 beliefs proposed by Ellis. The present study with a nonclinical sample of female college students (N = 114) evaluated the relationships among the IBT, locus of control, cognitive set for success and failure, interpersonal assertion, and depression. As predicted, irrationality on the IBT and on several of its specific‐belief components was related significantly to externality, negative cognitive set, unassertiveness, and self‐reported depressive symptomatology. Multiple regression analyses indicated that locus of control, irrationality, and cognitive set predicted assertion and that locus of control and irrationality predicted depression.