Eighty undergraduate students participated in an investigation of the effects on acquisition of immediate versus 30-second delay of reinforcement under either known or unknown response contingency conditions. The students in the four experimental conditions were required to depress three buttons in proper senquence. Following a correct response, the proper sequence systematically changed. The task was to discover the rule which determined how the sequence changed. Criterion was three consecutive correct responses. A two-way analysis of variance demonstrated significant main effects for both the temporal reinforcement delay and response contingency condition, and for the interaction effect. Immediate reinforcement facilitated acquisition better than reinforcement that was delayed 30-seconds. Acquisition was also better facilitated when the subject had knowledge of the response contingency. The interaction effect demonstrated that the difference between acquisition rates for immediate and delayed reinforcement increased when the subject was unaware of the response contingency. The results affirmed the findings of research supporting the use of immediate and contingent reinforcement for acquisition. (Author/GK)