Postpartum depression (PPD) is a mood disorder which can adaptively alter maternal socialisation strategies. Our objective was to investigate differences in ethnotheories and childrearing practices of mothers with low (N = 46) and high (N = 45) intensity of PPD. The Brazilian version of Edinburgh Postnatal Depression Scale was applied at 3, 8 and 36 months. Scales concerning socialisation goals, childrearing beliefs and practices were administered at 36 months. Mothers of both groups did not differ regarding socialisation goals, but they differed concerning childrearing beliefs and practices. High-intensity PPD mothers scored less on interdependent and autonomous beliefs and also on autonomous childrearing practices. Therefore, maternal perceptions about ethnotheories and childrearing practices are ways of cognition which can be modulated by PPD. PPD would affect perceptions about more costly cares that require exclusive attention (autonomous) to further affect perceptions about less costly cares that require shared attention (interdependent).