National survey on religious and secular attitudes and behaviour.Surveys on religion in Dutch society, also known as social and cultural developments in the Netherlands have been conducted in the winters of 1979/1980, 1985/1986, 1990/1991, 1995/1996, 2000/2001, 2005/2006.They are part of a long-standing research program, aimed at longitudinal and cross-national research with a strong (a) substantial multi-disciplinary focus on religiosity, values, in-group solidarity and out-group derogation as well as a strong (b) methodological focus on high quality data, valid measurements and innovative data-collection designs.The most recent data collection for 2010-2011 improves possibilities to test hypotheses on processes of secularization and individualization, spanning a period of thirty years.