Research on neighborhoods and health has been growing. However, studies have not investigated the association of specific neighborhood measures, including socioeconomic and built environments, with cancer incidence or outcomes. We developed the California Neighborhoods Data System (CNDS), an integrated system of small area-level measures of socioeconomic and built environments for California, which can be readily linked to individual-level geocoded records. The CNDS includes measures such as socioeconomic status, population density, racial residential segregation, ethnic enclaves, distance to hospitals, walkable destinations, and street connectivity. Linking the CNDS to geocoded cancer patient information from the California Cancer Registry, we demonstrate the variability of CNDS measures by neighborhood socioeconomic status and predominant race/ethnicity for the 7,049 California census tracts, as well as by patient race/ethnicity. The CNDS represents an efficient and cost-effective resource for cancer epidemiology and control. It expands our ability to understand the role of neighborhoods with regard to cancer incidence and outcomes. Used in conjunction with cancer registry data, these additional contextual measures enable the type of transdisciplinary, "cells-to-society" research that is now being recognized as necessary for addressing population disparities in cancer incidence and outcomes.