This study is an assessment of the relevance of subjective efficacy and ideal family size as predictors of favorability toward birth control. The samples considered are male factory workers in five developing nations. The effects of ideal family size and subjective efficacy are generally strong relative to those of education and the other social variables that are considered. The focus of the study is an analysis of whether subjective efficacy and ideal family size function more as independent determinants or more as intervening variables. Overall these psychological variables function more as independent determinants than as intervening variables, but in some samples these two functions are equally important.