Involuntary secondhand smoke (SHS) exposure in homes is an entirely preventable public health threat that disproportionately burdens young children in communities of low socioeconomic position. Breathe Free For Kids is a community-based participatory research (CBPR) initiative to evaluate the effectiveness of Ml compared with usual best practices (UBP) by having parents voluntarily adopt smoke-free home policies to protect children from SHS. The Motivational Interviewing intervention protocol was developed in conjunction with community partners, integrated into a health department-sponsored home visiting program for high-risk children and other community-based agencies serving children, and delivered by trained community health workers.