A composite receptor method for PM-10 apportionment was evaluated to determine the stability of its solutions and to devise cost-effective measurement strategies. Aerosol samples used in the evaluation were collected during summer, 1982, by dichotomous samplers at three sites in the vicinity of Philadelphia, PA. The composite receptor method consisted of a wind-trajectory method, chemical mass balance (CMB), and multiple linear regression (MLR). Measured lead minus a CMB-derived correction for other sources was used as an independent variable in MLR, and MLR results for the Pb abundance in vehicle exhaust agreed with predictions of a model for vehicle emission factors. In resolving PM-10 into 11 components, scanning electron microscopy was essential for coal-fly ash and botanical matter, x-ray fluorescence (XRF) was needed for the sulfur-component and vehicle exhaust, and instrumental neutron activation analysis (INAA) was essential for fluidized catalytic crackers at refineries.