(1) Despite its high prevalence, the diagnostic delay of endometriosis is still estimated to be about 7 years. The objective of the present study is to understand the symptomatology of endometriosis in patients across various countries and to assess whether the severity of symptoms correlates with the diagnosed stage of disease. (2) An international online survey collected self-reported responses from 2964 participants from 59 countries. Finalization of the questionnaire and its distribution was achieved by cooperation with various organizations and centers around the globe. (3) Chronic pain presentation remarkably increased between Stage 1 and 2 (16.2% and 32.2%, respectively). The prevalence of pain only around and during menstruation was negatively correlated to the stage, presenting with 15.4% and 6.9% in Stages 1 and 4, respectively. Atypical presentation of pain was most commonly reported in stage 4 (11.4%). Pain related solely to triggering factors was the most uncommon presentation of pain (3.2%). (4) Characteristics of pain and quality of life tend to differ depending on the reported stage of the endometriosis. Further research may allow a better stage estimation and identification of patients with alarming symptomatic presentation indicative of a progressive stage, even those that are not yet laparoscopically diagnosed.