Objective: This study aimed to evaluate the validity and reliability of the Turkish version of Client Attachment to Therapist Scale (CATS-TR) which provides a framework for measuring and conceptualizing the relationship between the therapist and the client. Method: The study included 191 individuals with a mean age of 24.41 years who had received a minimum of 5 and a maximum of 15 sessions of therapy for different psychological problems. All participants completed the CATS-TR, the Early Close Relationships-R (ECR-R), the Bell Object Relations Inventory (BORRTI), and the Working Alliance Inventory (WAI-SF), and a Client Information Form handed to the clients in a closed envelope by their respective therapists. Results: Exploratory and Confirmatory Factor Analysis results indicated an acceptable fit for the CATS-TR which comprised the Secure, Fearful/ Avoidant and Preoccupied/Merger subscales, with internal consistency levels ranging between 0.71 and 0.85. Criterion validity analyses showed that the scores on the CATS-TR Fearful/Avoidant and Preoccupied/Merger subscales correlated with the scores on the ECR-R Avoidance/Anxiety subdimesnions and the BORRTI Object Relations subdimension in the expected directions. Also, the mean score on the CATS-TR Secure Attachment subscale was a significant predictor of the therapeutic alliance assessed by the WAI-SF and its subscales. Conclusion: This study has demonstrated that the CATS-TR has an acceptable level of validity and reliability with results indicating its usefulness for research and clinical settings in Turkey investigating the common factors bringing about change in psychotherapy.