Psychological factors of emotional distress and cognition have an important role in the understanding and management of endometriosis; however, their temporal relationship with key pain variables is not fully understood. This exploratory study sought to establish the temporal relationship between psychological and pain-related factors in a 12-month prospective study of 208 Australian women with endometriosis. Participants, aged 18-50 years and living in Australia, were recruited via social media and completed baseline (May 2019) and 12-month follow-up (June 2020) surveys. Participants who reported a diagnosis of endometriosis and menses in the past 12 months were included in the study. Structural equation modelling was used to determine the temporal effects of psychological and pain-related factors in endometriosis. In a covariate-adjusted model, baseline emotional distress was the only variable to predict pain catastrophizing (β = .24, p < .01), functional pain disability (β = .16, p < .05) and concomitant emotional distress (β = .55, p < .001) 12 months later, adjusting for age and chronic illness. Women who exhibit symptoms of distress may be at risk of poorer psychological and physical function at 12 months. Further research is required to understand the impact of psychological management early in the disease course.