Systems Analysis and Simulation in Ecology, Volume II, concludes the original concept for Systems Analysis and Simulation in Ecology, and at the same time initiates a continuing series under the same title. The original idea, in 1968, was to draw together a collection of systems ecology articles as a convenient benchmark to the state of this emerging new field and as a stimulus to broader interest. These purposes will continue to motivate the series in highlighting, from time to time, accomplishments, trends, and prospects. The present volume is organized into four parts. Part I outlines for ecologists the concepts upon which systems science as a discipline is built. Part II presents example applications of systems analysis methods to ecosystems. Part III is devoted to new theory, including an investigation into the feasibility of several nonlinear formulations for use in compartment modeling of ecosystems; and the important topic of connectivity in systems. Part IV presents a sampling of systems ecology applications. It provides a reasonably balanced and accurate picture of the practical capability of ecological systems analysis and simulation. Performance does not come up to publicity, but prospects for rapid improvement are good given a willingness to let pragmatism guide sound scientific development without demanding unrealistic short-term successes.