This report describes an analysis that was conducted to investigate the development of roughness in pavements using data collected for the Long-Term Pavement Performance (LTPP) program. The analysis included: (1) investigation of time-sequence roughness data collected at test sections to study trends in the development of roughness, (2) comparison between International Roughness Index and Ride Number (3) development of models to predict changes in roughness (4) investigation of roughness characteristics of new flexible and rigid pavements built for Specific Pavement Studies in LTPP program, and (5) investigation of roughness characteristics of flexible and rigid pavements and were subjected to different rehabilitation strategies.