Influence of Infant Mother Class on Mother Behavior in Giving Stimulation and Development of Toddler Age 24-36 Month at Kedung Mundu Health Center Semarang CityToddler period is an important period in child growth and development. In Indonesia the number of children aged under five is 23.7 million, 10.4% of the total population of Indonesia. Growth and development is one indicator of child health monitoring. Provision of stimulation is an important thing that children need. This stimulation or stimulation can be done alone by the mother. Parents in providing stimulation or stimulation need to have knowledge and ability about stimulation of growth and development. One effort to improve the mother's knowledge stimulation grows, namely through the Toddler Class.The purpose of this research is to analyze the influence of mother-to-child class on the change of mother's behavior in giving stimulation of development. This research is Pre-experiment design with One-Group Pretest-Posttest Design research design. Sampling method used is total sampling. Data collection techniques using questionnaires. The technique of data analysis using t-dependent test and wilcoxon test.The results of the research conducted on 19 respondents showed that there is a significant influence on the mother's under five years of mother's behavior and the development of rough motorcycle aged 24-36 months at Kedung Mundu Health Center Semarang City.The conclusion of this study is expected health workers can motivate mothers to be able to provide growth stimulation in order to detect early if there is a deviation.