Molecular dynamics computer simulations are used to study several related time-dependent processes: solvation dynamics, rotational and vibrational relaxation taking place at the water liquid/vapor interface, and at the interface between water and an immiscible organic liquids. A unified description of the effects of the interface structure and polarity on these phenomena is presented, exploiting recent advances in experimental and theoretical understanding of the liquid interface region. Implications for interfacial chemical reaction dynamics are discussed. (C) 2009 Elsevier B. V. All rights reserved.