In the Laurentian Great Lakes region, commercial activities involving live fish bait, horticultural and water-garden plants, biological supplies, pets, and live food are the principal pathways for intentional introductions of live aquatic organisms. We sampled species for sale in these trades and found that the risks of new invasions and of spreading known invaders are high. Moreover, most animals were identified by common name only, and even though scientific names were more often applied to plants, consumers cannot be certain what species they are receiving because misidentification is common. Finally, 90 percent of plant orders arrived contaminated with unordered live organisms. The policy goal of US and Canadian national and state or provincial agencies is to reduce the risk of harmful introductions. Our results demonstrate that meeting this goal will require accurate identification of species by vendors, the removal of known and likely invasive species from trade, and reductions in the number of contaminant organisms.