Background <p>Cognitive behavioral therapy (CBT) is an effective treatment for childhood anxiety, but CBT protocols suited for primary care are lacking, which limits accessibility. This study aimed to develop a CBT intervention for children aged 7–12 years with mild to moderate anxiety suitable for Swedish primary care.</p> Methods <p>A participatory design approach was used, including workshops and interviews with parents (<i>n</i> = 6), therapists (<i>n</i> = 12), managers (<i>n</i> = 3), and CBT experts (<i>n</i> = 3). Following development of a preliminary CBT protocol, children (<i>n</i> = 4) and their parents piloted the intervention. Subsequent interviews with children, parents, and therapists explored treatment experiences and informed further refinement.</p> Results <p>The developed intervention, <i>Step by Step</i>, followed a stepped-care model comprising two steps: Step 1 (four group sessions and one individual session) and Step 2 (three additional individual sessions if needed). Interviews with children, parents, and therapists piloting the intervention resulted in three themes with corresponding subthemes: (a) acceptance - sense of not being alone; appreciation of interactive session activities; (b) feasibility - suitable in primary care but a therapeutic challenge to shift from group to individual format; more time in group needed (c) appropriateness - flexibility promotes relevance and fit; strategies contribute to learning and behavioral change.</p> Conclusions <p>This study illustrates how an intervention can be developed to fit a specific setting. A preliminary version of the stepped-care intervention yielded feedback that will be used to finalize the protocol. Larger-scale clinical trials are planned to evaluate feasibility and effectiveness.</p>