Since the first International Workshop on "Brain Phosphoproteins", the proceedings of which were published as "Progress in Brain Research" Volume 56, developments have progressed rapidly. Interim discoveries such as the effect of phorbol diesters on protein kinase C, the calcium-releasing effect of inositol triphosphate and direct evidence for the participation of protein kinases in regulating ion channels, indicate that the field has shifted from the early emphasis on characterization of substrates and kinases to key issues of function. While future direction was apparent at the 1981 meeting, the second International meeting in 1985, "Phosphoproteins in Neuronal Function", contained much specific empirical detail as well as some detailed models of phosphoprotein function. The hope that brain protein phosphorylation represents a critical step in relating neuronal function to brain chemistry has been realized, and the present volume illustrates the specificity achieved in defining the particular physiological processes that are closely related to the phosphorylation state of brain proteins. This book keeps workers within the field, and their associates in related fields, abreast with present activity, and points to future developments that will more closely define the central role of brain phosphoproteins in understanding the physiological chemistry of nerve cells.