We recently expanded this data set to include measures of religiosity. The most
useful sources of international data on church attendance and religious beliefs seem to be
the surveys reported in the three waves of the
World Values Survey or WVS(1981-84,mostly 1981; 1990-93, mostly 1990; and 1995-97, mostly 1995 and 1996), the two reports on religion by the International Social Survey Programme
or ISSP(1990-93,mostly 1991; and 1998-2000, mostly 1998), and the Gallup Millennium Survey (1999). Another wave of the WVS applies to 2000-01 and will soon be available.