This volume is the product of a technical session organized for the 2002 Geological Society of America Annual Meeting in recognition of Isaac Kaplan's many contributions to various fields of geochemistry. As Kaplan enters his sixth decade of scientific investigation, it is fair to say that his work has touched or influenced innumerable scientists either directly or indirectly. Readers of this volume are presented with a collection of 29 papers written by former students, post-doctoral researchers, friends and colleagues from countries all over the world (including Sweden, Japan, Taiwan, New Zealand, Australia, Israel and the United States) from the fields of stable isotope, forensic, environmental and petroleum geochemistry, atmospheric chemistry and cosmochemistry.The stable isotope section includes papers investigating climate change, diagenesis, recent sediment and petroleum geochemistry and cosmochemistry problems. The forensic and environmental geochemistry section includes a variety of papers ranging from trace metals in soils to atmospheric CO2 projections. The petroleum geochemistry section includes both basic research and applied geochemistry papers. The ancient and recent sediments section contains papers ranging from carbon flux in modern sediments to Precambrian microfossils. All of the articles together cover a broad range of geochemical studies and represent the diverse and distinguished career of Isaac Kaplan.