The objective of this article is to provide insight in the five-step development process of the best evidence, best practice intervention for obese young children ‘AanTafel!’. A set of requirements for intervention development was developed to guide the data inquiry: the use of theory, influencing factors, tailoring, multi-disciplinarity, duration/frequency and evaluation and monitoring. Step I retrieved evidence from clinical guidelines, followed by a systematic review with meta-analysis (Step II) and an extended literature review (Step III). Evidence was consistent with regard to parent-focus, targeting family level, including diet, physical activity and behaviour change techniques and tailoring to age. However, no evidence or inconsistent evidence emerged from the theory-basis, group-versus-individual sessions, face-to-face contact versus Internet-mediated contact, which disciplines to involve and how to involve them, as well as intervention duration and intensity. Hence, practice-based insights from parental interviews (Step IV) and involved therapists were added and subsequently integrated to the intervention ‘AanTafel!’ (Step V). ‘AanTafel!’ is a multi-component, multi-disciplinary, family-based, parent-focused, age-specific intervention, which is tailored to individual children and families with a duration of 1 year, and using a combination of individual and group sessions as well as a Web-based learning module. Changes in scientific working principles with regard to data collection, reporting and translation to guidelines are required. Practice and science may benefit from close collaboration in designing, implementing and evaluating interventions.