America faces the threat of biological attack. Stopping such attacks requires the fast detection of pathogens. Fluorescence of key biological substances provides a real-time technique for detecting airborne pathogens. Pacific Scientific Instruments has already demonstrated that Bioni, a bio-aerosol sensor based on a CW UV-emitting AlGaN diode laser, can detect within seconds the dispersal of threat organisms in postal sorting facilities and other settings. Minimization of false positives is especially important in bio-threat detection, since false positives can lead to undue public alarm, stoppages of work, and costly clean-ups. Although Bioni has proven itself as a fast and sensitive trigger, its selectivity is limited by its single-wavelength excitation and single-band fluorescence detection. In this paper, we describe the development of BioLert, which uses simultaneous excitation and detection at multiple wavelengths to improve specificity and guard against false positives. Initial experimental results on the detection of individual spores of Bacillus globigii (BG), as well as discrimination against inert aerosols, will be discussed.