A number of apparently unrelated phenomena in biological systems (e.g., biopolymer aggregation, cell-cell interactions, ion transport across membranes) arise from the special properties of charged surfaces. A sym posium entitled Electrical Double Layers in Biology , which took place at the Toronto meeting of the Electrochemical Society, 12-17 May 1985, focused on the common features of these phenomena. The papers presented at that symposium are collected here and they illustrate ways in which an under standing of electrical double layers can elucidate a problem in Biology. An example of this approach can be seen from the paper I presented on ion transport and excitation, where the unusual ion flows during nerve excitation are actually expected if one includes the effects of electrical double layers at membrane surfaces. Furthermore, the selectivity of the ion channels in these membranes can be better understood on this basis. Other presentations account for such observations as the changes in spacing between muscle proteins during contraction, the interactions of red cells to form rouleaux, the electrical properties of algal cell membranes, electrokinetic potentials during blood flow in arteries, etc. I trust that these papers will indicate the value of electrochemistry in the study of biological systems, an area of research usually called Bioelectrochemistry, and will encourage biologists to use these ideas when approaching related problems.