Background: A growing body of evidence advocates a multidisciplinary, family-focused approach to childhood obesity management, but there is a need to explore familial factors associated with intervention success.Aim: This study explored the relationship between adult BMI change and child BMI SDS change following completion of a community-based, lifestyle change intervention for obese children and families (Getting Our Active Lifestyles Started (GOALS)).Method: Sixty of 121 families with overweight children completed the GOALS intervention between September 2006 and March 2009.Complete pre-and post-intervention (6 months) BMI data was available for 47 of these families, 26 of whom attended 12-month follow-up. Child BMI was converted to age-and sex-specific standard deviation scores (SDS) using the 1990 UK growth references.Results: There was a strong correlation between adult BMI change and child BMI SDS change from pre-to post-intervention (r = 0.53, p < 0.001) and from pre-intervention to 12-month follow up (r = 0.72, p < 0.001). Over both time periods, children with adults who reduced BMI were more likely to reduce BMI SDS (p < 0.01) and showed a greater reduction in BMI SDS (p < 0.01) than children with adults who maintained or increased BMI.Conclusion: The results showed a strong positive association between adult BMI change and child BMI SDS change, particularly during the post-intervention period where therapeutic contact was minimal. The findings suggest active involvement of adult family members in the weight loss process improves child treatment outcomes.