Complementary food for breast milk (MP-ASI) is additional food given to infants not only breast milk after the baby is 6 months old until the baby is 24 months old. This study aims to determine the behavior of mothers in providing complementary feeding (MP ASI) to children aged 0-6 months in Brukan Hamlet, Kalisat Village, Rembang District, Pasuuan Regency. This study uses a method with a descriptive approach to mothers who have children aged 0-6 months. The sample in this study were mothers who have children aged 0-6 months as many as 32 respondents. The sampling technique used was simple random sampling. The results of the validity and rehabilitation test (0.865) The reliability and research were carried out on June 9-12 2021 while data processing was carried out on July 11, 2021. The results showed that most of the 21 (65.6%) behavioral respondents in giving MP ASI were negative and for those who behave positively as many as 11 (34.4%) respondents. Mother's negative behavior is more than positive mother's behavior because most of the mothers still live with old parents who have very minimal knowledge about when it's best for children to be given complementary foods, so mothers give complementary foods (MP ASI) early.