This systematic review examines quantitative literature on Autistic identity to identify factors associated with positive Autistic identity development and to understand the relationship between Autistic identity and mental health and wellbeing. A total of 3,617 studies were screened, and 20 met the inclusion criteria. The review found that external acceptance and support are significant factors in developing a positive Autistic identity, while individual factors such as age, gender, and Autistic characteristics were largely nonsignificant or inconclusive. Positive Autistic identity was associated with improved mental health and wellbeing, and peer support and self-directed resources may be valuable mechanisms for supporting Autistic individuals in cultivating a positive Autistic identity. The review highlights the need for broad support that meets the diverse needs of Autistic people and suggests that peer support groups could be effective in fostering positive identity development. Future research should evaluate the long-term impacts of such support on identity development.This systematic review examines quantitative literature on Autistic identity to identify factors associated with positive Autistic identity development and to understand the relationship between Autistic identity and mental health and wellbeing. A total of 3,617 studies were screened, and 20 met the inclusion criteria. The review found that external acceptance and support are significant factors in developing a positive Autistic identity, while individual factors such as age, gender, and Autistic characteristics were largely nonsignificant or inconclusive. Positive Autistic identity was associated with improved mental health and wellbeing, and peer support and self-directed resources may be valuable mechanisms for supporting Autistic individuals in cultivating a positive Autistic identity. The review highlights the need for broad support that meets the diverse needs of Autistic people and suggests that peer support groups could be effective in fostering positive identity development. Future research should evaluate the long-term impacts of such support on identity development.