Three field studies compared helping behavior across a sample of 24 small, medium and large cities across the United States. The relationship of helping to statistics reflecting the demographic, social, and economic characteristics of these communities was then examined. The strongest predictors of city differences in helping were population size, population density, economic purchasing power and, to a somewhat lesser extent, walking speed. Changes in several community variables over the past decade were also associated with helping: population size, economic well-being as measured by both purchasing power and poverty rates, and crime rates. These data were compared to similar data collected 13-15 years ago.