This stage includes the following: Systematic reviews of the literature on the topics of encouraging i. parental cessation, ii.reducing child tobacco smoke exposure (TSE), and iii.reducing tobacco smoke air pollution in homes; consultations with experts worldwide; conduct of interviews with parents (n=65) and professionals (n=15) to understand parental perceptions of tobacco smoke exposure, and barriers to protection of children from TSE; and development of an initial intervention program. This stage draws on a social marketing approach and employs in-depth interviews to identify barriers to behavior change and relevant behavior-change recommendations, tailored to the intervention population, and to test the acceptability of program components.