Background: This paper builds on a Cochrane-Campbell systematic review of interventions that reduce harms and promote reintegration in street-connected children and young people focusing on intervention outcomes. The aim of the present analysis is to explore questions raised in the systematic review over the potential role of service engagement in mediating outcomes of relevant interventions. Objective: The paper summarises engagement-related findings from quantitative intervention evaluations with street-connected populations of children and young people, as reported by study authors. It seeks to contribute to theoretical and methodological understandings of service engagement with street-connected youth populations and to highlight gaps in current knowledge. Methods: Drawing on the original search for the Cochrane-Campbell review, we re-screened search results in our database and included quantitative findings if relevant to our current research questions, regardless of study design. Additionally, we sought new study publications from authors whose work was included in the original systematic review. The discussion explores relevant data from five studies included in the original systematic review, ten studies excluded from the review, and two studies published after the completion of the review. Results: The measures of service engagement in the included studies focused on treatment attendance, "level of engagement", and service satisfaction. Evidence on the impact of service engagement on other outcomes in interventions for street-connected children and young people was limited. Available data on the predictors and impact of service engagement were mixed and appear not to provide robust support for common hypotheses in the relevant context.