Web:
European social survey: www.europeansocialsurvey.org
Eurostat New Cronos: Eurostat Statistics portal
Centre for Multilevel modelling: useful resources and links. MLwiN software and manuals and courses on basic and advanced multilevel modelling. www.cmm.bristol.ac.uk/
Centre for Census and Survey Research: courses on advanced data analysis and multilevel modelling. Research is carried out here on methods for combining data and multi-level modelling and the ESS. See www.ccsr.ac.uk

Books:
Snijders T and Bosker R (1999) 'Multilevel modelling' Sage. - a good introduction to the topic.
Goldstein (2003) 'Multilevel statistical models' Edward Arnold - a more technical discussion.

Papers:
Fieldhouse E, Tranmer M, Russell A (2007) "Something about young people or something about elections? Electoral participation of young people in Europe: evidence from a multilevel analysis of the European Social Survey." European Journal of Political Research