1Although previous research has shown that experiencing an injury can act as a catalyst for self-2 development, research that has examined the concept of sport injury-related growth (SIRG) 3 remains largely descriptive. This study aimed to address this by developing a substantive theory 4 to explain the processes through which injured athletes experienced SIRG. Using Strauss and 5Corbin's (1998) variant of grounded theory, 37 injured athletes competing in a range of sports 6 and competitive levels participated in qualitative interviews. Interviews (N=70) and data analysis 7were conducted over a period of 24 months. Transcripts were analyzed using open, axial, and 8 selective coding. Quality criteria used were fit, relevance, workability, and modifiability. The 9 grounded theory produced (i.e., Theory of Sport Injury-Related Growth) suggests a number of 10 internal (i.e., personality, coping styles, knowledge and prior experience, and perceived social 11 support) and external factors (i.e., cultural scripts, physical resources, time, and received social 12 support) enable injured athletes to transform their injury into an opportunity for growth and 13 development. The mechanisms through which this occurs are meta-cognitions, positive 14 reappraisal, positive emotions, and facilitative responses. This theory offers a number of exciting 15 avenues for future research, and provides medical personnel and practicing sport psychologists 16 with a detailed explanation of how sport injury can lead to growth experiences. 17 18