<p>The first three years of life represent a sensitive period for the emergence of psychosocial competencies that shape long-term cognitive, social, and emotional outcomes. Despite increasing recognition of early childhood development as a public health priority, limited empirical evidence exists on parental knowledge and its determinants in urban Tanzanian contexts. This study examined the level and predictors of parents’ knowledge of early psychosocial development among children aged 0 to 3 years in Temeke Municipality, Dar es Salaam. A cross-sectional study was conducted among 422 parents or caregivers attending child health clinics in eight randomly selected public health facilities. Data were collected using a Kiswahili-adapted Knowledge of Infant Development Inventory for Parents (KIDI-P) and analysed using descriptive statistics and multivariate regression models. Nearly half of the respondents (44.8%) demonstrated poor knowledge of psychosocial development, particularly in the socio-emotional domain. Higher knowledge was associated with having more children, being married, and possessing at least a secondary education. In contrast, longer residential duration and reliance on professional consultations predicted lower knowledge. Direct caregiving experience and peer discussions were the most potent positive informational predictors. Parental knowledge of early psychosocial development in Temeke Municipality remains suboptimal, with socio-emotional understanding particularly limited. Strengthening parental education through health system integration, peer-support mechanisms, and targeted community engagement could enhance nurturing care and promote optimal child outcomes.</p>