In 4 experiments, pigeons received autoshaping with various combinations of three stimuli, A, B, and C, before test trials in which responding during all three stimuli, ABC, was compared with that during a three-element control compound, DEF, which had been consistently paired with food. Fairing A, B, and C individually with food resulted in similar rates of responding during ABC and DEF (Experiments 1 and 2). Responding was faster, however, during ABC than during DEF after training in which food was signaled by the pairs of stimuli (AB, AC, and BC; Experiment 1). Responding was also faster during ABC than during DEF after training involving reinforced ((+)) and nonreinforced (degrees) trials of the form ABC+ A degrees BC degrees, followed by A(+) BC+ (Experiment 2), or AB(+) BC+ B degrees (Experiments 3 and 4). The results are consistent with those of a configural analysis of summation.