Preface. H. Pick, Jr. A.D. Pick, Foreword. C. Trevarthen, Moving Experiences: Perceiving as Action With a Sense of Purpose. J. Delafield-Butt, B. Schoegler, The Ubiquitous Nature of Tau. M. Grealy, J. Smith, G-J. Pepping, Thinking Tau: The Emergence of Intrinsic Guidance. A.P. Georgopoulos, A Tribute to Tau. D. Young, Navigation. C. von Hofsten, Ideas on the Development and Control of Actions. W.H. Warren, Action-Scaled Information for the Visual Control of Locomotion. J. Thomson, Promoting the Development of Pedestrian Traffic Skills in Young Children. R. van der Weel, C. Craig, A. van der Meer, The Rate of Change of Tau.