This report, the 10th in a series of the National Governor's Association (NGA) project "Facilitating Improvement of State Programs for Pregnant Women and Children," describes ongoing efforts of facilitating development of provider participation in Medicaid. The objective of the project is to identify where participation problems result in gaps in available services or insufficient access to care. The first part of the report presents the definition of physician participation, approaches to measuring physician participation, and participation by organized providers. The second part deals with using Medicaid files to examine participation in order to develop an effective monitoring system. The third part reviews two examples of adapting Medicaid data to monitor participation: linking provider and claims data in Texas and relying on claims files in Pennsylvania. The fourth part presents other alternatives for examining aspects of the provider participation such as monitoring private physician participation with a level of effort definition, monitoring new patients served by participating physicians, monitoring care rendered by organized providers, and monitoring changes in the availability of care in a geographic area. The appendix includes information on physician participation in Medicaid from recent literature. Contains 16 references. (AP)