BACKGROUND:Comprehensive understanding of the referral process and factors associated with it will assist general dentist (GD)-periodontist relationships and benefit patient care and services. Non-clinical factors (NCFs) influence clinical decision making but are rarely considered. The objective of this review is to identify NCFs found to be associated with referrals to periodontal specialists. METHODS:A systematic review of English-language literature was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. An electronic search was carried out using the Cumulative Index to Nursing and Allied Health Literature, Dentistry and Oral Sciences Sources, and PubMed. Search terms used included: 1) refer; 2) referral; 3) periodontal; and 4) periodontist. Potentially relevant publications were analyzed in detail using predetermined inclusion and exclusion criteria. Selected papers were assessed using the Mixed Methods Appraisal Tool, and data extracted were thematically synthesized. RESULTS:Ten studies that examined NCFs fulfilled inclusion criteria. Four NCF themes identified were practice-, GD-, patient-, and periodontist-related factors. CONCLUSIONS:Limited literature is available on NCFs associated with referrals to periodontal specialists. Within the limits of this systematic review, NCFs affecting the referral process are practice-, GD-, patient-, and periodontist-related factors. These vary among different GD populations studied. Factors that could be targeted to improve referral processes include geographic location, undergraduate training, and continuing professional development.