Stakeholder involvement in intervention development has become increasingly popular and is understood as crucial for successful implementation. However, methodological difficulties persist regarding the implementation of appropriate participatory methods to engage children and collect relevant information for intervention development. This paper discusses four creative, qualitative methods – a brainstorming task, an individual letter, a story-based task, and a focus group task – and compares their suitability to generate relevant information for early intervention development. These four methods were used in the early stages of a project aiming to develop a peer relationship intervention and were analysed using thematic analysis. Based on theoretical considerations, information categories (a) definition aspects, (b) context factors, and (c) change mechanisms were of interest, while (d) examples and experience and (e) additional information were identified as prevalent categories through inductive thematic analysis. Definition was a prevalent theme generated by the brainstorming task, although the sticky note format limited the depth of individual answers. The secret letter, which allowed children to share ideas privately, was found to be useful for generating more in-depth reflections on definitions and personal experiences. Stories and focus group discussions were found to be useful for generating varied context factors and change mechanisms, although stories also generated fictional elements and external solutions. Providing different qualitative methods and allowing children to choose how they prefer to communicate their thoughts proved important for collecting authentic, in-depth information.