Samenvatting

This study describes the development of a program theory for play therapy as an intervention for children and

young people with mild intellectual disabilities and difficulties with aggression regulation. The program theory

was developed in collaboration with registered play therapists through focus groups and individual interviews.

The aim was to gain insight into explicit and implicit knowledge regarding therapeutic practice with this target

group.

Data collection took place in three phases: first, a focus group with experienced play therapists; second, interviews

with therapists working specifically with the target group; and finally, a comparative round with

therapists working with a general client population. The interviews were analyzed thematically, with additional

attention to the type of knowledge expressed, including explicit, implicit, or unique knowledge specific to the

target group.

The results show that play therapists work from a client-centered attitude, strongly focusing on building a

therapeutic relationship and providing a safe environment. Collaboration with the child’s support system and the

use of micro-interventions during play were identified as key elements. This study represents the first step toward

establishing a theoretical foundation for play therapy as a complex intervention for this specific target group.