During the Particulate Matter Technology Assessment and Characterization Study--New York (PMTACS-NY) in January/February 2004 a variety of modern aerosol measurement instruments were deployed at a field site on the campus of Queens College in Queens, New York. These instruments included the Aerodyne Aerosol Mass Spectrometer (Q-AMS), R&P Particulate Ambient Sulfate and Nitrate monitors (8400S&N), a Particle-into-liquid Sampler equipped with ion chromatographs (PILS-IC), an R&P FDMS TEOM, and several other techniques to measure physical aerosol properties. The PMTACS-NY 2004 winter campaign was designed to replicate measurements performed at this site during the PMTACS-NY 2001 summer campaign. The field campaign experienced significant meteorological variability and extreme weather conditions, which together with local and regional aerosol and precursor emissions generated a wide range of PM concentrations at the site, with significant changes in physical aerosol properties as well as aerosol composition as a function of particle size. Q-AMS quantification procedures and intercomparison studies of nonrefractory species mass concentrations measured with the Q-AMS and other colocated instruments (PILS-IC, R&P 8400 S/N, FDMS TEOM, and Sunset Labs OC Analyzer) are presented. The size-resolved aerosol composition over the measurement period and its variation with time of the day, regional meteorology and local source impacts are discussed. Results obtained during this field campaign are compared to data from the PMTACS-NY 2001 summer campaign, where aerosol composition was observed to have higher sulfate, significantly lower nitrate content and overall mean aerosol mass size distributions with larger mode diameters.