Recent advances in polymer chemistry and stabilization and increasing consumer demands for longer lasting products require use of faster, more reliable methods to evaluate durability of materials. The controversy continues: How to properly test materials for resistance to sunlight, rain, and atmospheric acid and salt? Proper use of results from accelerated tests depends on understanding: 1) how the exposure stresses in the accelerated test match those found in field use and 2) impact of variability in results from accelerated tests and outdoor exposures. STP 1202 presents 15 peer-reviewed papers that cover research in characterization of exposure tests, and new developments in exposure equipment and exposure test design.