Subjects differing in interpersonal construct differentiation completed a measure of religious attitude, a measure of attitudinal confidence, and a 20‐item religious behavior self‐report inventory. High‐confidence subjects exhibited greater attitude‐behavior consistency (r = .69) than did low‐confidence subjects (r = .51). Despite high power (N = 313), high‐ and low‐differentiation subjects did not differ significantly (r = .61 and .66, respectively), indicating that the role of differentiation as a direct mediator of non‐interpersonal attitude‐behavior consistency is a comparatively small one. But the influence of attitudinal confidence on attitude‐behavior consistency was larger for low‐differentiation subjects (r = .75 for high confidence, .51 for low) than for high‐differentiation subjects (r = .68 for high confidence, .50 for low), suggesting that interpersonal construct system development may indirectly influence the relationship of non‐interpersonal attitudes and behaviors.