From one of the largest social studies education programs in the country, four social studies professors have crafted an annotated collection of 500 gateway web sites useful to social studies teachers. The urls are categorized by major social studies content strands with web sites  linked to the NCSS Themes. Each web site selected by the authors was reviewed and had to meet 4 criteria: Comprehensiveness, to insure a breath and depth of information and resources Durability, to insure its long-term usefulness Self-renewing, to insure up-to-date information and improvements to the web site Credibility, to insure lack of bias and accuracy