Could there be a better time to be a life scientist? In the past two decades, a host of new techniques have been added to the tool chests of biochemists and molecular biologists. A wonderful benefit of the basic scientific research that fueled the advances in these fields is the wide variety of direct applications in agriculture and medicine. Even with all of these advances, and with the accompanying explosion in computer and information technology, it is clear that the depth of our ignorance vastly exceeds the breadth of our knowledge about complex organisms at the molecular level. Any new techniques or materials that allow us to extend our research-based knowledge should be w- comed and utilized to their fullest potentials. With the cloning of the green fluorescent protein (GFP) from Aequorea victoria in 1992, another valuable tool was added to the arsenal. In Green Fluorescent Proteins: Applications and Protocols examples of how GFP can be utilized in a variety of fields are presented. Although the text has chapters that emphasize different areas of s- cialization, it is not meant to send molecular biologists to one section, botanists to another, and clinicians to still another. Perhaps the most valuable exchange for people in any discipline will come from seeing how others have been able to apply GFP in fields outside of their immediate areas of expertise. GFP from Aequorea victoria is a fluorescent marker protein, and there are certainly other useful fluorophore markers.