Phthalates are used as plasticizers in many industrial and consumer products. Urinary biomonitoring has shown widespread human exposure to phthalates, with workers having especially high exposures. Phthalates can be present in workplace air as either aerosols or vapors depending on source materials, vapor pressure, and processing temperatures. We sought to develop a dual-phase air sampling method for 6 phthalates, dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), benzyl butyl phthalate (BzBP), di(2-ethylhexyl) phthalate (DEHP), and di-n-octyl phthalate (DnOP), adaptable to aerosol inlets with known particle collection characteristics. Collection media consisted of a quartz fiber filter and XAD-2 resin. Limit of detection (LOD) and limit of quantification (LOQ) were determined for each phthalate. Phthalate recoveries were evaluated at 3×, 10× and 30× the LOQ, and after storage at −21 °C and 21 °C. Media were Soxhlet extracted in 10% diethyl ether in hexanes along with an extraction surrogate, di-n-pentyl phthalate-d4. Gas chromatography/mass spectrometry was performed to quantify the phthalate diesters using di(2-ethylhexyl) phthalate-d4 as an internal standard. Estimated LODs were 1 µg per sample (BzBP, DEHP, and DnOP), 2 µg per sample (DMP and DBP), and 5 µg per sample (DEP). Mean recoveries under static conditions were 85–104% for DBP, BzBP, DEHP, and DnOP; but <70% for DMP and DEP at 3× and 10× the LOQ. After air was pulled through spiked samples, DMP and DEP recoveries improved to 74–81%. After storage for 62 days, phthalate recovery was better at −21 °C than at 21 °C. Method accuracy was best for DBP, BzBP, DEHP, and DnOP (range 11–18%), and less so for DMP (28%) and DEP (29%).