In organizing the present volume, we had two intentions. The first was to present the best current understanding of the mechanisms of calcium mobilization during excitation contraction coupling of smooth muscle at a level suited to the needs of professionals interested in smooth muscle pharmacology and pathophysiology, while remaining appreciable by graduate and medical students. The second intention was to provide in sight into present-day controversies, as well as the latest ad vances achieved by researchers in this field. Thus, we have thor oughly discussed both the techniques and the concepts derived from their application. An attempt has also been made here to answer a number of profoundly important questions: What are the mechanisms and agents responsible for the control of contractility? What are the accompanying changes in the state of intracellular calcium ions and the mechanisms responsible for them? How does the regula tion of contractility occur directly at the level of the actomyosin activity? What role do gap junctions play in cell-to-cell coupling? What are the roles of cholinergic, adrenergic, peptidergic, and nonadrenergic noncholinergic interactions in calcium mobiliza tion in smooth muscle? What changes occur in hypertension? The impact of these recent techniques on future research is also reflected upon."