The molecular basis of disease is the driving force in biomedical research. Gene detection, quantification, and localization are required to determine disease pathogenesis. In as much as DNA is the genetic potential in a particular organism, RNA and protein expression are the functional result of our genetic program. "Techniques in Localization of Gene Expression" describes in great detail the methods used to quantify and localize gene expression. Sensitive detection of gene expression is hindered by poor recovery or preservation of target sequences. "Techniques" emphasizes optimized methods to ensure full recovery and preservation of targets from specimen acquisition through detection of specific targets and final analysis. Situ Analyses of cells and tissues are also discussed. One of the weaknesses in biomedical research has been the use of in vitro model systems consisting of cell lines that may or may not mimic the in vivo conditions. These model systems are necessary to ask several questions on cells and tissues with controlled variables in the absence of strategies to ask many questions at the same time. Multiparameter analysis can circumvent the necessity of in vitro model systems by allowing many questions to be answered on a cell or tissue at a single point in time. Using fluorescent dyes, on can answer many questions about a particular cell or tissue. One color, one question is an overriding theme of this book. The limitations of this approach are the number of colors in the spectrum and our ability to resolve them. Readers will find working protocols that have been developed and used routinely in the author's laboratory. Representative applications will be described using the various gene quantification and localization protocols to illustrate the utility of the techniques.