The organophosphate class of compounds includes common herbicides as well as highly toxic nerve gases whose detection is important from an environmental and a public safety perspective. We describe here a fluorescence turn-on sensor array for the rapid detection and quantitation of relevant organophosphates in neutral water. The array elements self-assemble from commercially available dyes and PAMAM dendrimers, and sensing is based on an indicator displacement assay. Data interpretation through pattern recognition methods (PCA, LDA) showed excellent cluster separation and sample classification. In addition, we were also able to use this system for simultaneous differentiation and quantitative analysis of methylphosphonate (a nerve gas byproduct), glyphosate (a ubiquitous herbicide), and inorganic phosphate over a wide range of concentrations (10 μM to 2 mM).