This study investigated whether chronic adolescent social stress, genetic background, and their interaction influence later morphine stimulation, sensitization, and consumption. The data show genetic background and stress altered morphine behaviors. Specifically, adolescent social stress attenuated morphine sensitization in C57BL/6J mice, but not BALB/cJ mice. Adolescent social stress did not influence morphine stimulation or consumption in either strain. Together, our findings show that genetic and environmental factors influence behaviors related to opioid abuse.