Evidence is increasingly pointing towards the importance of early life strategies to prevent childhood overweight and obesity. This systematic review synthesizes qualitative research concerning parental perceptions regarding behaviours for preventing overweight and obesity in young children. During May and June 2008, a range of electronic databases were searched and together with lateral searching techniques 21 studies were identified for review. Data extraction and synthesis using thematic content analysis revealed six organizing and 32 finer level themes. These related to child factors, family dynamics, parenting, knowledge and beliefs, extra-familial influences and resources and environment. Themes were mapped to a socioecological model which illustrated how factors at individual, interpersonal, community, organizational and societal levels interact in complex ways to impact on parental perceptions about healthy behaviours for preventing child overweight. Although parents suggested several ideas to promote healthy child weight-related behaviours, many of their views concerned perceived barriers, some of which may be amenable to practical intervention. Furthermore, intergenerational influences on parental health beliefs and knowledge suggest that health promotion strategies may be more effective if directed at the wider family, rather than parents alone. Significantly, many parents believed strategies to promote healthy weight should start early in a child's life.