Study Objective: To analyze the nature and accuracy of social media (Facebook) content related to endometriosis., Design: Retrospective content analysis., Setting: Social media platform, Facebook., Participants: Social media posts on Facebook endometriosis pages., Interventions: A search of public Facebook pages was performed using the key word "endometriosis." Posts from the month-long study period were categorized and analyzed for accuracy. Two independent researchers used thematic evaluation to place posts into the following 11 categories: educational, emotional support, advocacy, discussion, events, humor, promotional, recipes, resources, surveys, and other. Posts categorized as educational were further subcategorized and reviewed. Each posted fact was cross-referenced in peer-reviewed scientific journals to determine whether the claim made was evidence-based. Engagement in a post was calculated by taking the sum of comments, shares, and reactions., Measurements and Main Results: A total of 53 Facebook pages meeting inclusion criteria were identified and 1464 posts from the study period were evaluated. Emotional support posts comprised the largest category of posts (48%) followed by educational posts (21%). Within the educational category, the epidemiology and pathophysiology subcategory comprised the largest group (42.0%) followed by the symptom's subcategory (19.6%). Post category had an effect on the amount of post engagement (p-value <.001) with emotional posts generating 70% of the overall engagement. The subcategories of the educational posts demonstrated a similar effect on engagement (p-value <.001). Posts were more engaging if they contained epidemiology and pathophysiology information with 44% of all engagement of educational posts occurring within this subcategory. Educational posts were found to be 93.93% accurate. There was no correlation between post engagement and post information accuracy (p-value = .312)., Conclusion: Facebook pages offer emotional support and education to people with endometriosis. Most information found in these Facebook pages is evidence-based. Clinicians should consider discussing the use of Facebook pages with their patients diagnosed with endometriosis., (Copyright © 2021 AAGL. Published by Elsevier Inc. All rights reserved.)