Impacts of crowding and host quality on boll weevil reproductive development and occurrence of diapause characters were investigated under controlled environmental conditions. Crowding and poor host quality influenced fat accumulation, reproductive commitment, and diapause status of females, but did not influence mating activity. Moderation of crowding and improvement in host quality tended to be accompanied by increased reproductive commitment and decreased diapause incidence. Crowding and host quality influenced fat accumulation in males, but did not appear to influence gonadal or seminal vesicle condition. Experimental conditions influenced diapause status of males, but effects were different than for females. Implications of the results to other diapause studies and control programs are discussed.