A change in land use has been found to alter the components of the hydrological cycle through its effects on evapotranspiration. This influences planning and management of water resources. The Workshop, from which this volume was derived, was organized in this context to discuss processes and techniques relevant to estimating evapotranspiration of communities ranging from agricultural to forested lands. Its objectives were to provide a forum for exchange of ideas, to gather up-to-date information on the state of the art, and to identify priority areas for future research.The eighteen papers in this volume have been selected from those presented at the Workshop on the basis of technical quality and subject matter coverage and result in a valuable contribution to our current understanding of evapotranspiration.