Although curiosity is an essential element to work with children, it can hinder the therapist's initiative due to the child's reaction to it (immediately defending against it). This paper seeks to further develop this concept within the context of non-directive play therapy (NDPT). The grounded theory study sought the opinions of twenty-five practising UK play therapists through semi-structured qualitative interviews. The findings highlight the therapists' overall resistance towards acknowledging ‘professional curiosity’ in their work with child clients. Outcomes suggest that ‘professional curiosity’ can be set within an attachment framework for both non-directive play therapists and child clients. The findings of this study have implications for the practice of not only non-directive play therapists, but also other professionals involved in the health and social care field.