Samples of atmospheric particles were analyzed for organic and elemental analysis at three sites in Houston, TX. Samples for the quantification of individual organic compounds were collected during August 2000--September 2000 and analyzed for molecular speciation. A chemical mass balance (CMB) model was applied to the organic speciation data to estimate the contributions of the eight possible sources to the fine particulate matter mass in Houston. Major contributors to PM2.5 included gasoline vehicles, diesel vehicles, meat cooking and wood combustion with smaller contributions from vegetative detritus. It was found that PM2.5 mass was also dominated by other organics and secondary sulfate. Samples for airborne metal analysis were collected and analyzed by two different chemical analysis methods; Inductively Coupled-Plasma Mass Spectrometry (ICP-MS) and X-Ray Fluorescence (XRF). Positive matrix factorization (PMF) was applied to the elemental concentration data for source identification and apportionment. PMF resolved five physically interpretable factors at each site of which four were found to be common at all sites: crustal material, road dust, wood burning, and sea salt. The composition of the remaining factor was similar, but not identical at the three sites and had an elemental composition similar to industrial combustion. Crustal material is the most important contributor at each site.