•Children's conceptualization of school snacking was explored using drawings.•Children consume both healthy and unhealthy products as snack.•Barriers and facilitators for healthy snacking were explored using a completion technique.•Perceived healthiness was the main motivator for the consumption of healthy snacks.•Hedonic aspects were the main motivators for the consumption of unhealthy snacks.•Potential actions to promote healthy snacking habits at schools were identified. Snacks consumed at school are an important source of energy and nutrients in children's diets. Understanding the factors that underlie children and mothers' choices of school snacks can contribute to the development of strategies to promote healthier eating patterns. In this context, the aims of the present work were: i) to explore children's conceptualization of school snacking, and ii) to identify children and mothers' perceived barriers and facilitators to healthy snacking in the school environment. Two studies with 518 children and 1183 mothers were carried out. In Study 1, children (n = 255) were asked to draw a child eating a snack at school. In Study 2, five incomplete dialogues about school snacks were presented to participants (263 children and 1183 mothers), who had to complete them using their own words. Data were analyzed using content analysis. The drawings showed that school snacking frequently occurs during the recess while children do other activities, such as playing football or other games. Fruit, sandwiches, cookies and juices were the foods and beverages most frequently included in the drawings. Responses to the dialogues enabled the identification of barriers to healthy snacking in the school environment, which were related to children's positive hedonic reaction towards unhealthy foods, the sales of unhealthy products in the school canteen, lack of time to prepare home-made snacks and mothers' perception that children can eat unhealthy snacks once in a while. In addition, the existence of a school snacking policy was mentioned as a facilitator for healthy snacking. Potential additional actions to promote healthy snacking habits in the school environment were identified.