Current best practice and international consensus recommends that concussed athletes progress through the graduated return to sport steps, a process designed to progressively re-introduce physical activity to ensure athletes are "ready" to return to sport. However, this conceptualization is limited as it almost completely ignores psychological factors. This study attempted to provide an initial conceptualization of the psychological factors involved in being ready to return to sport following a concussion. Approached from a critical realist perspective, we conducted a series of semi-structured interviews (M = 72 min, range = 56-100 min) with 22 key knowledge holders (14 females) involved in high school, university, and professional contact and collision sports, including: formerly concussed athletes (n = 4), coaches (n = 5), athletic therapists (n = 5), physiotherapists (n = 4), nurse practitioner (n = 1), and sports medicine physicians (n = 3). The interview questions focused on factors participants believed were involved in athletes being ready (or not ready) to return to sport after a concussion. We used a coding reliability approach to thematic analysis and found the following psychological factors were salient among participants: frustration (injury and recovery process), confidence (health status and post-concussion abilities), fear (roster status and subsequent injury), and pressure (internal and external sources). Results of this study provide a preliminary conceptual understanding of the psychological factors involved in returning athletes to sport following a concussion. These findings also appear to have practical implications for allied health professionals who are involved in the rehabilitation of concussed athletes.