Introduction: To adopt a conduct it is necessary to identify internal factors that affect it. Objectives: To identify mothers´ knowledge, attitudes and perceptions on children less than 3 year-old nutrition. Design: Quantitative qualitative study, descriptive, exploratory. Location: Villa Maria del Triunfo Human Settlements, Lima, Peru. Participants: Mothers of children less than 3 year-old. Interventions: Following informed consent, for the quantitative phase phase we applied a questionnaire of 10 closed questions with dichotomous responses on knowledge and 10 questions with Likert’s response categories on attitudes to 161 mothers; and for the qualitative we did 28 depth interviews and 4 focus groups to identify perceptions were conducted to 68 mothers. Main outcome measures: Level of knowledge, type of attitudes and perceptions on breastfeeding (BF), complementary feeding (CF) and f...