Schwartz (1982, 1988) found that a pretraining of contingent reinforcement interferes with subsequent rule discovery. The present study investigated the effects of schedule imposed sequential and quantitative constraints (Timberlake & Allison, 1974) on task performance in a subsequent test phase. Sixty-four Ss, students of the University of Duesseldorf, were assigned at random to one of four experimental conditions, differing according to the presence vs. absence of sequential and quantitative constraints, respectively. Discrimination-learning performance and variability during test phase were significantly better for Ss experiencing sequential constraint during treatment. In contrast, the introduction of a quantitative restriction during treatment had no statistically significant effects on test phase performance.