Objective:
Deliberate Practice (DP) is a promising approach to improve psychotherapy outcomes and skill acquisition. Based on theoretically derived core components of DP in psychotherapy, the aim of this study is to develop assessment instruments for measuring behaviours related to and attitudes towards DP.

Method:
Two item sets were generated associated to DP's core components in psychotherapy and characteristics of DP. Two exploratory factor analyses were conducted to develop two scales (DP Behaviours [DPB] and DP Attitudes [DPA]). Data were collected from prospective psychotherapists in Germany (N = 199). Furthermore, in a subsample (N = 138) construct validity was tested using correlational analysis with convergent and discriminant constructs.

Results:
The analysis supported a two-factor structure (activities and feedback and expert involvement) for and construct validity of the DPB scale, indicating associations in expected directions. For the DPA scale, one factor emerged indicating a generalised attitude towards excellence and improvement. Construct validity was partially supported, with convergent correlations in expected directions, but inconsistencies regarding discriminant validity.

Conclusion:
The scales developed in this study demonstrate potential for linking self-assessments of DP to psychotherapy outcomes. Future research needs to consider the predictive validity of DP's core components in relation to psychotherapy outcomes and broader factors influencing DPB and DPA, such as a culture of excellence or trusting and healthy relationships with experts.