Studies on deformation characteristics of early-age Jointed Plan Concrete Pavements (JPCP) subjected to pure environmental loading has drawn significant interest as it is believed that the early-age deformation of Portland Cement Concrete (PCC) slab could result in the loss of pavement smoothness and the tensile stresses induced by these deformations could result in early-age cracking. However, the complex interaction of several environmental factors has resulted in difficulties in predicting the JPCP deformation characteristics under environmental loading. This book discusses the early-age behaviors of JPCP under environmental loading. The slab deformations associated with temperature and moisture were analyzed using measured vertical displacements and pavement surface profile measurements. The variation of smoothness at different measurement times and locations are analyzed and discussed. The early-age deformation behavior of instrumented JPCP under environmental loading was also simulated using Finite Element (FE) programs using the equivalent temperature difference concept.