Abstract: A Polarization Fluorescence Photoactivation Localization Microscopy (P-FPALM) system and method are provided to simultaneously image the localizations and fluorescence anisotropics of large numbers of single molecules within a sample. The system modifies known FPALM systems by adding a polarizing beam splitter. The beam splitter polarizes emissions perpendicular and parallel to an axis in the sample to allow spatially separate imaging of fluorescence emitted from a sample. The system includes lenses and mirrors so that the separate, polarized beams are detected simultaneously. The present invention includes methods of using the system to image localizations and fluorescence anisotropics of single molecules, and methods of using data obtained with the system to predict 3-D orientation of the molecules. The system and method achieve substantially improved lateral resolution within even dense samples over known microscopic imaging techniques, and does not compromise speed or sensitivity.