The performance of six human infants (aged 16 to 20 weeks) was compared under a conjugate- versus a continuous- reinforcement schedule. The contingent visual stimulus, a sequence of 5 colored lights, their intensity varying in proportion to response amplitude under the conjugate hut not under the continuous schedule, was presented alone and together with a constant auditory contingent stimulus—chimes placed behind the lights—under both schedules. The target operant response—a foot press of a vertical panel—produced the lights with/without the tinkling chimes. A reversal design counterbalanced with alternating treatments was implemented for each half of the participants. Visual inspection of the graphed-operant frequencies for all six infants, and one-tail binomial tests, showed at p < 0.008 that: (a) the two contingent-stimulus complexes, visual alone and visual-plus auditory, functioned as reinforcers of leg thrusts under both reinforcement schedules; the visual-plus-auditory consequence was a more effective reinforcer for leg-thrust operants than was the visual consequence alone; and, (c) compared to the continuous CRF schedule, the conjugate-reinforcement schedule generated higher peak responding. (PsycINFO Database Record (c) 2016 APA, all rights reserved)