Expected performance of cotton varieties is best predicted by past performance over multiple sites and years. The objective of this work has been to develop a computer program that assists with comparing performance of cotton varieties over multiple state variety tests. To meet this objective, COTVAR was developed and released in February 2007. COTVAR utilizes data from state variety tests in Arkansas, Louisiana, Mississippi, Missouri, and Tennessee. Each year, cotton varieties are evaluated at approximately 30 sites over these five states. Test performances from each state are made available in annual variety test publications and on the internet. COTVAR enables easy comparison of varieties over the states by integrating data from multiple states into one file. Users can select specific test sites or regions and compare varieties, which are characterized by type (convention, single or stacked transgenes) and by status (commercially available, experimental, or obsolete). Data generated include yield, lint fraction, fiber properties, and specific morphological and host plant resistance traits. Plans are underway to expand COTVAR to include data from all states that conduct cotton variety testing. COTVAR may be accessed at http://cotvar.uaex.edu/intro.asp.