Studies assessing associations between the characteristics of places and health-related outcomes depend largely on individual-aggregated survey data with administratively-defined area boundaries set by the census bureau. Residential variation in health is examined with units of observation constituted by spatial zones in contiguous urban areas (e.g., census tracts). Such units are neither independent nor discrete. They do not correlate well with resident perceptions of neighbourhood. Their correspondence with theoretically meaningful and potentially more informative levels of scale is not clear. Socioeconomic status is the primary measure drawn from administrative data and, in individual-aggregated form, is often assumed to indirectly represent "context" despite being a direct measure of population composition. There is a need to expand consideration of spatial influences beyond aggregated data from census surveys, and to directly capture environmental characteristics in research on health and place. This presentation will describe the development and application of a comprehensive multi-data source geographic information system (GIS) to understand how social and built environmental factors relate to important public health problems in Montréal, Canada. This GIS, named MEGAPHONE (Montréal Epidemiologic and Geographic Analysis of Population Health Outcomes and Neighbourhood Effects), integrates a broad and diverse array of spatial databases and analysis tools. It is relational, hierarchical and semi-automated, with a menu-based interface to geo-reference, extract and analyse spatial data. An extensive spectrum of exposures is accounted for, with indicators explicitly linked to constructs in a hierarchical indicator classification system. Data can be extracted at different levels of scale to facilitate multi-level modelling. Other analytic options include geographically weighted regression and buffers centred on households, street sections, or higher order units. Databasing and data structuring will be discussed alongside system limitations and sustainability considerations. Use of the system will be illustrated through analyses of adverse birth outcomes, injection drug use, cardiometabolic risk and mortality.