The proceedings of a special technical session dealing with the addition of Ca based materials to waters and soils for the purpose of restoring or enhancing fisheries in acidified waters are contained in this volume. The session was part of the North American Fisheries Society’s annual meeting sponsored by the Water Quality Section of the Society. While the concept of liming is not new, the extent of the recent research, demonstrations and applications reported at the conference is enlightening. Six countries are represented by government, state and private sector participants. The scope of activities reported in the following 23 papers range from the simple to the very complex addition of liming materials to ponds, lakes, streams and watersheds. This volume of presentations is broad and impressive as are the methods used in the actual application of the neutralizing materials. Those programs that are demonstration application oriented are deploying techniques that are either new or modifications of existing technology.