These Proceedings have been assembled from papers presented at the Conference on Models of Biological Growth and Spread, held at the German Cancer Research Centre Heidelberg and at the Institute of Applied Mathematics of the University of Heidelberg, July 16-21, 1979. The main theme of the conference was the mathematical representation of biolog- ical populations with an underlying spatial structure. An important feature of such populations is that they and/or their individual com- ponents may interact with each other. Such interactions may be due to external disturbances, internal regulatory...