Members from all four Weed Science Society of America (WSSA) regions in the United States ranked the research need to “develop new methods for controlling the movement of herbicides and their metabolites into ground water, surface water, and air” first of six major weed science research needs. Canadian members ranked the need to “devise more efficient and less costly weed control technology for conservation-tillage crop-production systems” first; but they also gave high ratings to “improve base knowledge of weed science, improve applicator training, and transfer of information to Extension Service personnel, farm producers, and administrators” and to “discover new ecological, biological, and non-chemical methods of weed control.” The needs to “develop improved methods of increasing the tolerance of crops to herbicides” and to “develop new technology for control of perennial weeds of crops and rangeland” were ranked low. The WSSA Research Committee, at the request of WSSA Presidents J. D. Riggleman (1985) and O. C. Burnside (1986), asked 977 members to rank weed science research needs. The members (ca 50% of the active membership in North America) were selected at random from every other state, federal, industry, and “other” member of each state or province from the up-to-date list of the WSSA business office. Within the highest ranked priority research need, the 422 U.S. and Canadian respondents consistently ranked the research areas (a) to “develop new application techniques that minimize or eliminate herbicides and their residues in air and water”, and (b) to “conduct research to regulate movement of herbicides through the soil profile to avoid contamination of ground water” high, regardless of the type of employment. They emphasized increasing research on the morningglory (Ipomoea spp. # IPOXX) complex, yellow nutsedge (Cyperus esculentus L. # CYPES), quackgrass [Agropyron repens (L.) Beauv. # AGREE], and several other weeds. More members, regardless of region or type of employment, ranked conservation tillage the most important crop or situation that needed new and improved weed control technology.