Abstract: Single fluorescent molecules in a flowing sample stream are distinguished and identified using only a single laser excitation wavelength. A sample stream is formed containing a dilute mixture of single molecule fluorophores, wherein each one of the fluorophores is serially ordered in the sample stream. The sample stream is illuminated with s single excitation wavelength laser effective to excite each fluorophore one at a time. Fluorescence emission photons from each said fluorophore are detected. A burst size is determined for each fluorophore to identify each fluorophore. A pulsed laser may be used, where burst size and an intra-burst fluorescence decay rate for each fluorophore are determined simultaneously from the detected fluorescence emission photons. The burst size and the decay rate are correlated to identify each fluorophore.