Children's tobacco smoke exposure (CTSE) is a public health concern, particularly in low-income and minority communities. Interventions to reduce CTSE have had modest success, and so research must identify mechanisms to improve intervention efficacy. This study investigated mediators of CTSE reduction in an intervention designed to facilitate CTSE protection and maternal smoking abstinence. We analyzed data from the Babies Living Safe and Smokefree (BLiSS) trial, which evaluated the efficacy of a multilevel behavioral smoking intervention initiated in community clinics serving low-income mothers. We estimated direct and indirect effects to evaluate the role of two mediators of the intervention on CTSE at post-intervention follow-up: mothers' skills in managing smoking urges and their protective behaviors to shield children from TSE. CTSE was measured using mothers' reports and child cotinine (a CTSE biomarker). The BLiSS intervention was linked to statistically significant lower longitudinal reported CTSE directly and indirectly by increasing mothers' urge management skills and CTSE protection behaviors (