The sources of particulate lead in houses in the London Borough of Richmond, England have been investigated using automated scanning electron microscopy in conjunction with energy dispersive X-ray spectroscopy. Compositional and size information was collected on lead-bearing particles from density and size fractionated floor dusts from 16 residences of various ages. A classification scheme based on the analysis of different types of lead source particles was used to categorize the house dust particles as either auto exhaust, road dust, garden soil, paint, high temperature process emissions, lead of common origin or miscellaneous lead-bearing. Classification results based on both populations of particles and estimated particle volumes suggest that paint, road dust and garden soil are the major contributors of particulate lead to the Richmond households. The primary contributing source in the 64-1000-microm size range of the house dusts appears to be paint. In the 0-64-microm size fraction of the dusts paint, road dust and garden soil all make significant contributions. Variations in the contributions made by the major sources appear to be unrelated to the age of the homes.