This article presents results to date produced by a team charged with evaluating the National Academies Keck Futures Initiative, a 15-year US$ 40 million program to facilitate interdisciplinary research in the United States. The team has developed and tested promising quantitative measures of the integration (I) and specialization (S) of research outputs, the former essential to evaluating the impact of the program. Both measures are based on Thomson-ISI Web of Knowledge subject categories. ‘I’ measures the cognitive distance (dispersion) among the subject categories of journals cited in a body of research. ‘S’ measures the spread of subject categories in which a body of research is published. Pilot results for samples from researchers drawn from 22 diverse subject categories show what appears to be a surprisingly high level of interdisciplinarity. Correlations between integration and the degree of co-authorship of selected bodies of research show a low degree of association.