This report establishes the 15 Index standards and provides a detailed methodology for assessing open space in New York City neighborhoods. We piloted the OSI methodology on the Lower East Side of Manhattan, which was chosen because of its variety of open spaces, rich residential diversity and vibrant history of park and garden advocacy. The pilot found that the Lower East Side performs very well with regard to community gardens, acres of active recreation, and access to parks. It also found, however, that the neighborhood has an urban tree canopy cover of only 14%, far below the US Forest Service's 44% recommendation for that community. And the assessment found that the Lower East Side parks have very little green, natural ground surfacing within its parks.