Background: Little is known about the effect of case-formulation based cognitive behaviour therapy (CBT) for anxious children. Aim: The present study explores the feasibility of case-formulation driven CBT for anxious children. Parents were involved in treatment as either co-facilitators (involved only as the child's assistants, treatment being primarily directed at the child), or as co-clients (parents received therapy targeting theoretically established maintaining mechanisms; children received half of the sessions, parents the other half). Method: Feasibility of the case-formulation driven CBT was established by comparing the completion rate and the percentage of children free of anxiety after treatment, with manualized treatments reported in existing meta-analyses. Children aged 7–12 years and their parents participated (n = 54). Families were assessed at pre- and posttreatment and at 6-month follow-up. Results: All families completed treatment and the percentage of recovery in the case-formulation driven approach was comparable to results obtained in manualized treatments. Conclusion: The findings from this stage I study supports the notion that a case-formulation driven approach to CBT may be a feasible option when selecting treatment for anxious children; however, further studies must be conducted before firm conclusions can be drawn.