Introduction: The social determinants of health (SDoH) can play a significant role in a person’s overall wellbeing. This is especially true for adults with mental illness and mental health disorders. In this study, we describe the SDoH of patients presenting to an academic, inner-city emergency department (ED) with an acute mental health complaint (AMHC). Methods: We prospectively identified and enrolled a convenience sample of patients presenting to an ED with an annual census of 85,000 visits. Participants provided informed written consent, and completed a questionnaire package containing questions related to demographics and SDoH. As well, participants were asked to complete four mental health, quality of life, and recovery validated patient-reported outcome measures. Results: A total 108 participants were enrolled in this study, of which 65% were male, aged 37.5 years (IQR 26.7-50.3), 56% Caucasian, and 22% Aboriginal. Depression was the primary diagnosis reported by 55% of participants, with 58.9% meeting the PhQ-9 cutoff for moderate-severe depression. The highest level of educational achievement for 44% of participants was high school or less, with 75% reporting being unemployed. Almost half (45%) reported engaging in less than two hours of structured activity each week. Thirty eight percent of participants reported living in their own apartment, with 25% reporting being homeless and 17% living in a single-room housing unit. The majority of participants (56%) sampled were not satisfied with their housing, and 67% were actively looking for new housing. Sixty percent of participants reported smoking cigarettes daily and 40% reported weekly cannabis use. A total of 11% of the sample reported that they did not have access to clean drinking water; 35% worried that their food would run out, and 47% reported cutting the size of meals due to a lack of money. Conclusion: This study lends evidence towards the circumstances in which patients presenting to the ED with an AMHC live and work. A considerable proportion of patients reported homelessness or being marginally housed, lack access to clean drinking water and sufficient food, and high rates of unemployment. Mitigating the effects of harmful social determinants is critical for optimal health of this population. Future work is needed to clarify the role of the ED in the surveillance, screening, and intervention of SDoH for this vulnerable patient group.