A major challenge in monitoring indoor exposures to nanoparticles is the selection and effective use of suitable instrumentation. Comparability, portability, response time, and reliability are important selection criteria in addition to reasonable cost. Amongst these criteria, instrument comparability is especially critical due to the requirement for multiple instruments in a single exposure assessment and the lack of reference standards for instrument calibration. Testing and verifying instrument comparability, therefore, is essential to ensure the reliability of exposure assessment data. In this study, a variety of portable and non-portable direct-reading instruments, including scanning mobility particle sizers, condensation particle counters, aerodynamic particle sizers, diffusion charger and aerosol mass monitors, were deployed simultaneously. Instrument performance was evaluated in a room-sized environmentally-controlled chamber with the goal of recommending a suite of instruments to provide particle number, surface area, particle size distribution and mass measurements with an acceptable level of uncertainty. The instrumental strategy was then applied to monitoring background aerosols in a typical workplace setting, where laser printers provided a point source for monitoring response time and comparing peak-to-background signals. The study also explored filter-based methods for collecting nanoparticles for subsequent elemental analysis using inductively-coupled plasma mass spectroscopy (ICP-MS).