Twenty-eight greenhouse screening materials, with predetermined airflow resistance values, were evaluated for exclusion of silverleaf whitefly (Bemisia argentifolii Perring & Bellows) and thrips from a mixed-species population. Screens differed in exclusion efficacy, as a percentage of the fiberglass window screen control and at an approach velocity of at 92 m/min, from –35 to 94% for silverleaf whitefly and from –13 to 95% for thrips. Seventeen screens excluded more silverleaf whitefly, whereas seven excluded more thrips than the window screen control. One material differentially excluded whitefly over thrips; many more differentially excluded thrips over whitefly. Airflow resistance, indicative of mesh hole size, did not necessarily correspond with degree of exclusion. Though two high-resistance screens, No-Thrips and Econet S, excluded both pests, not all materials characterized as highly resistant to airflow provided significant exclusion. Exclusion of both pests was also attained with three moderate resistance screens, BugBed 123, BugBed 85, Pak 44×44, and one low-resistance screen, BugBed 110UV.