Treatment fidelity is widely accepted as a critical component of successful psychological program implementation and treatment integrity. The current study is a critical interpretive synthesis of the review and evaluation literature on Treatment fidelity in psychosocial interventions in the last decade with an aim to explore the emphasis placed by researchers on: i) definitions of treatment fidelity; ii) different components of treatment fidelity; and iii) existing strategies to enhance treatment fidelity in clinical practice. This encompasses ongoing clinician training, mentoring and supervision; provision of robust, cost efficient and portable suite of complimentary-tools. The results of the meta-evaluation highlighted researchers attached varying importance to strategies to enhance treatment fidelity in clinical practice. Several recommendations for treatment fidelity in clinical practice including: development of standardised definitions of treatment fidelity within an overarching treatment fidelity Model, incorporating measurement of clinician and client fidelity (through use of competence and adherence scales), and support for investment in professional development for clinicians. Areas of focus for future research include further examination of the linkage between clinician fidelity to client outcomes, and exploration of the value of measuring treatment fidelity overtime.