This work summarizes the results of a series of comprehensive studies on particulate matter (PM) carried out in Spain from 1999 to 2001. Monitoring sites were selected in accordance with different climatic and geographic conditions as well as anthropogenic influences, varying from rural background to urban curb-side sites. Measurements were carried out with gravimetric high-volume samplers and with automatic devices for different PM grain sizes, focusing on PM10 and PM2.5. A simultaneous meteorology study was performed to assess the influence of air masses and to detect long-range transport processes, especially African dust outbreaks, affecting the PM levels in the Iberian Peninsula and the Canary Islands. Mean values, chemical compositions and source apportionment analyses were obtained and discussed as a function of the different monitoring sites and during PM episodes.