The document provides four papers dealing with the availability and distribution of physicians' services in the United States. The first paper, Approaches to Measuring the Availability of Medical Services, distinguishes between conceptual and methodological approaches to examining the availability of medical services and attempts to illustrate how such approaches might be combined in analyses of physician supply and distribution. The second paper, Toward an Explanation of the Geographical Location of Physicians in the United States, attempts to identify the determinants of physician location and distribution, group them in appropriate categories of influence, and formulate hypotheses with which to test the explanatory power of the factors. The third document, a working paper entitled Distribution of Physicians by Specialty and Practice Patterns, examines the impact on policy of analyzing the physician population at different levels of specialty and professional activity aggregation. The final paper, Graduates of Foreign Medical Schools: Their Role in the U. S. Health Delivery System, examines immigration patterns and reviews current literature related to the "brain drain" issue and the impact of foreign physicians on U. S. medical care. Each paper incorporates relevant statistical data. (MW)