Fatal heroin overdose is preventable, yet remains a major public health issue in Baltimore City. Individual factors alone may not be sufficient to address overdose on a population level. Neighborhood characteristics offer an additional avenue for research. Concentrated disadvantage is one such trait and is characterized by the concurrent concentration of poverty, unemployment, and female headed households, within specific locales. Concentrated disadvantage is prevalent in Baltimore City, and this in combination with the persistence of heroin use allows a unique opportunity to examine the association between neighborhood structural factors and fatal overdose rates. This study will investigate the role of neighborhood characteristics in fatal heroin overdose rates in Baltimore between 1980 and 2006 and pathways through which these factors may be associated. To achieve this, this study proposes the following aims: to describe clusters of fatal heroin deaths in Baltimore neighborhoods in both space and time; to characterize the association between concentrated disadvantage and overdose rates, and the relationship between changes in each over time; and explore potential pathways such as collective efficacy through which concentrated disadvantage may be associated with fatal heroin overdose rates. Data on heroin overdose deaths in Baltimore between 1980 and 2006 will be obtained with the cooperation of the Office of the Chief Medical Examiner. Neighborhoods will be based on the community definitions of neighborhoods used by the Baltimore City Department of Planning. In meeting Aim 1, neighborhoods with clusters of the locations of overdose deaths in both space and time will be identified. To address Aim 2, these clusters will be spatially compared to, and adjusted for, property crimes, an indicator of neighborhood drug use, to assess if clusters are simply reflective of the underlying drug using population or other neighborhood factors. Decennial census data will be used to obtain annual rates of overdose deaths among 15-65 year old residents of each neighborhood and construct an index of concentrated disadvantage. Overdose rates per neighborhood will be analyzed longitudinally to assess whether concentrated disadvantage, and changes in concentrated disadvantage, are reflected in overdose rates. Lastly, Aim 3 will use cross-sectional survey data to explore pathways through which concentrated disadvantage may be associated with fatal heroin overdose rates. The proposed study could inform appropriate geographic locations for expanding overdose prevention and needle exchange programs in Baltimore, as well as provide an in-depth understanding of the spatial distribution and related neighborhood characteristics of overdose events. ? ? ?