This study investigates the fluorescence quenching of a polyphenyl based polyelectrolyte by positively charged macromolecules (proteins and dendrimers). This work shows that the fluorescence quenching of the dendrimer materials does not involve energy transfer or electron transfer but is correlated to the overall charge on the dendrimer and its size. The quenching is hypothesized to result from conformational changes that occur upon binding the polyelectrolyte to the protein or dendrimer. This mechanism is qualitatively different from that invoked for small-molecule analytes.