AbstractThere is some scientific evidence to support the applicability and preliminary effects of ACT as a parent intervention but more research is needed. In this pilot research, Acceptance and Commitment Therapy (ACT) is provided as a parent counseling therapy in order to increase psychological flexibility which in turn helps parents to choose attuned parenting behavior, invest in a helpful parent-child relationship, deal with feelings of incompetence, and cope with their own psychopathology. ACT parent counseling is developed for parents of children (3–18 years old) with psychiatric problems. The mean age of the parents (n = 101) was 47.1 years (range = 30–66). A repeated measures design was used including pretreatment, posttreatment, and 6-month follow-up measurements. The main outcomes were ACT measures (psychological flexibility, parental psychological inflexibility, and cognitive fusion). Secondary outcomes included parenting behavior, the quality of the parent-child interaction, parental competence, parental psychopathology, and the satisfaction with the treatment program. This is the first study we know of that showed statistically significant improvements on parental psychological flexibility, parenting behavior (except behavioral control), parent-child relations, parental competence, and parental internalizing psychopathology directly after treatment. At 6-month follow-up, significantly less conflicts, more parental competence, and less parental psychopathology was found. However, the improvements were not clinically significant, as calculated with the RCI. No control group was used in this uncontrolled pilot study but preliminary findings indicate that ACT parent counseling can help parents to increase psychological flexibility in order to choose more flexible and effective parenting behavior.