We develop a conceptual model for studying the antecedents and consequences of achieved and optimal levels of manufacturer-distributor (M-D) cooperation. We hypothesized that levels of market turbulence, competitive intensity, and the manufacturing firm's strategic type (i.e., prospector, analyzer, or defender) affected the optimal level of M-D cooperation. We also hypothesized that the level of under-and overachieving the optimal levels of cooperation negatively affects firm performance. The conceptual model is tested using empirical data collected from 295 manufacturing firms in the U.S. and validated using data collected from 104 distributors in the U.S. We also collect data from 255 Japanese manufacturing firms and 98 Japanese distributors. The empirical results support the model's hypotheses with only one unexpected finding: in the Japanese sample, overachieving the optimal level of cooperation has a greater negative effect on performance than underachieving. We conclude by discussing theoretical and managerial implications.