Research has shown the harmful potential of institutional care on young children; however, little is known about the consequences of institutional care on infants in Sub-Saharan Africa. We compared 35 Tanzanian children who were institutionalized at birth to 4 years of age with a matched group of 35 children who were institutionalized at 5 to 14 years of age. We examined adverse childhood experiences over the course of their entire lives, in their family of origin and in institutional care, and mental health problems at primary school age, such as depressive symptoms, aggressive behavior, and internalizing and externalizing problems. Results showed that early institutionalized children reported more adverse experiences during their time in institutional care and a greater variety of mental health problems than did late institutionalized children. Moreover, maltreatment in institutional care was positively related to mental health problems only in early institutionalized children. We conclude that adverse experiences in institutional care play an important role for early institutionalized children who need special care from adequately educated caregivers. Therefore, training concepts focusing on the needs of the youngest children have to be developed, tested, and established. Countries such as Tanzania need policies that apply to all orphanages to ensure an adequate standard of quality in childcare.