In this study, we investigated the relationship between fidelity of pivotal response treatment implementation and therapist characteristics, such as therapist personality, therapist-child relationship, therapist attitude toward evidence-based practices, and therapist experience. We also explored whether child age and autism symptom severity were related to pivotal response treatment fidelity. Participants were 41 level III certified pivotal response treatment therapists who recorded three 10-min pivotal response treatment sessions and completed four questionnaires to measure therapist characteristics. Results indicated that therapists' attitude toward evidence-based practices, specifically openness to innovation, and therapists' experience with pivotal response treatment significantly predicted fidelity of pivotal response treatment implementation. Cross-validation methods largely confirmed these findings. Therapist personality, therapist-child relationship, and child characteristics were not significantly related to pivotal response treatment fidelity. Implications for clinical practice and directions for future research are discussed.