Understanding why some children work on the streets while others live there, and how causal factors differ by gender, is important in developing effective services for them. This study examined these questions in Sudan using participant observation, qualitative interviews, and surveys of working boys (n = 1025), working girls (n = 192), street boys (n = 397), and street girls (n = 35). Street children were less likely than working children to have local families (66% and 77%, p<0.001), and more likely to have experienced some prior hardships, e.g. a mother's death (17% and 10%,p < 0.00 1), or coming from the war-torn south (30% and 10%, p<0.001). 70% of street children and 10% of working children had abused (i.e. sniffed and sucked) glue (p<0.001); initiating glue abuse often coincided with a transition from working to living on the streets. Within groups, conditions 'pushing' girls to street life were often harsher than for boys. For working girls, these included death of both parents (10% and 3%, p<0.001), and/or insufficient food at home (59% and 43%, p<0.001). For street girls, they included having a homeless family (23% and 9%, p=0.019), and/or insufficient food at home (63% and 40%,p=0.008), but street girls also more often reported boredom at home (80% and 48%, p<0.001). Services should be tailored to the particular needs of each group by gender, including community-based prevention, street-based health and safety interventions, and street child counseling and re-integration programs. 0 2007 Elsevier Ltd. All rights reserved.