Background & Aim: Today, due to social and domestic problems, a large number of children lose their families or guardians. Foster care is the last resort for many of these children. Conditional and emotional crises and maladaptations are problems that many of these children face in orphanage foster care units. Foster care workers and social workers play important roles in the  growth and development of these children. Having the knowledge of childrens growth and developmental stages helps these workers in better dealing with these children and makes these environments more pleasant for both workers and children. The goal of this study is to investigate the effects of teaching growth and developmental stages of children to on foster care worker's knowledge.
 Material and Methods: This study was conducted as a semi empirical study, 30 foster care workers and social workers participated in this educational program. A questionnaire, developed by researchers based on content of teaching program, was used. The questionnaire contained 40 questions about psycho-social needs of children at infancy, toddler and school age stages. Teaching program was 2 sessions (16 hours) and it be held with lecture, question and answer and role playing methods. The participants were asked to fill out the questionnaire before and two weeks after the program.
 Results: Findings show the mean scores in Knowledge of samples was 31.35 at pre-test and 38.22 at post-test. There was a significant statistical difference with paired t test in samples's knowledge before and after course of education (P=0.001).
 Conclusion: For receive better and more advantage of foster care units. It^,s need to more education for training parent foster care and more support are essential for successfully changing training and evaluating its impact.