Witnessing violence can have an adverse effect on children and adults. To determine the prevalence and selected correlates of witnessing violence among young children and their mothers, we consecutively recruited 143 parents (88% of those eligible) with children 1 to 5 years of age from the pediatric primary care clinic at Boston City Hospital. The final sample of 115 mothers were English-speaking, primarily minority and poor (76% living on < $10,000/year). In response to a standardized questionnaire, 10% of children were reported to have witnessed a knifing or shooting; 18% had witnessed shoving, kicking, or punching; and 47% had heard gunshots. Thirty-six percent of the mothers reported witnessing a knifing or shooting and 9% had been victims of a knifing or shooting. Mothers of children who had witnessed violence were more likely to limit their movements (80% vs 50%, p < .003) and were more concerned about safety (67% vs 24%, p < .001) compared to mothers whose children did not witness violence. This finding needs to be replicated in other settings, and potential consequences need to be identified.