One purpose of 'identification and prevention of dietary- and lifestyle-induced health effects in children and infants' (IDEFICS) is to implement a standardized community-based multi-component healthy eating intervention for younger children in eight different countries. The present study describes important influencing factors for dietary behaviors among children aged 2-8 years old in order to determine the best approaches for developing the dietary components of the standardized intervention. Twenty focus groups with children (74 boys, 81 girls) and 36 focus groups with 189 parents (28 men, 161 women) were conducted. Only in two countries, children mentioned receiving nutrition education at school. Rules at home and at school ranged from not allowing the consumption of unhealthy products to allowing everything. The same diversity was found for availability of (un)healthy products at home and school. Parents mentioned personal (lack of time, financial constraints, preferences), socio-environmental (family, peer influences), institutional (school policies) and physical-environmental (availability of unhealthy products, price, season) barriers for healthy eating. This focus group research provided valuable information to guide the first phase in the IDEFICS intervention development. There was a large variability in findings within countries. Interventions should be tailored at the personal and environmental level to increase the likelihood of behavioral change.