Background: Psychiatric research is increasingly interested in the influence of social and environmental contexts on human health. According to recent findings, specific impacts of urban upbringing relate to the heightened prevalence of mental disorders. Although this is a major societal problem, it remains unknown which environmental components (e.g., psychosocial stressors, rare nature exposure) are responsible. Method: We introduce Ambulatory Assessment (AA) as a methodological approach to investigate contextual influences. GPS-triggered electronic diaries are suitable to capture data in everyday life, gathering information on both context and mental states to assess dynamic processes in real-life and real-time. Result: A longitudinal study at the Central Institute for Mental Health in Mannheim combines AA, fMRI and epigenetic approaches to investigate environmental factors influencing mental health. The findings might be incorporated in urban planning to reduce mental disorders.