Between 1995 and 2005, 32 out of 42 European prison administrations had more prisoners in 2005 than in 1995. For 16 of those that experienced growth, the increase was more than 30 percent. For another nine countries, the increase was over 20 percent. Those countries with traditionally low levels of imprisonment--such as the Netherlands, Scandinavian/Nordic countries, and countries from the former Yugoslavia--have reported increases as large as countries from other parts of Europe. Ten countries recorded a decrease in their prison populations between 1995 and 2005, with 6 of them being members of the former Soviet Union. Criminal justice experts from nine countries that have experienced increases in prison populations since 2000 briefly identify factors in each of their countries they believe have contributed to the increase. The countries are Austria, Bosnia & Herzegovina, Finland, Luxembourg, Macedonia, the Netherlands, Poland, Spain, and the United Kingdom. Reports are also provided on factors related to decreases in countries' prison populations since 2000. These countries are Armenia, Latvia, Lithuania, Romania, the Russian Federation, and Turkey. 5 tables, annex