Environmental conditions such as soil temperature, moisture, and texture are major factors in establishing the geographic distribution, survivability, infection rate, and degree of yield losses associated with nematodes on cotton. The three major nematode pests of cotton vary in their response to environmental conditions. Root-knot nematode exists in most soil types in a zone in the United States with average temperatures from 59 to 81 F, has maximum infectivity at 72 F, and a minimum temperature range of 32 to 41 F for survival. Reniform nematode occurs over a wider range of soil types and is more common in soils with lower sand contents than root-knot or Columbia lance nematodes. Reniform nematode probably requires slightly higher minimum temperatures for survival and infection than root-knot nematode but is able to survive at lower soil moisture levels. Less is known about Columbia lance than the other two nematodes. Its geographic range appears to be limited to sandy soils and it is believed to have a higher temperature optimum for reproduction and can survive in much hotter and drier soils than root-knot or reniform nematodes. All three cause greater yield losses on plants which are under moisture or nutrient stress than on nonstressed plants. Information is needed on all aspects of environmental effects on nematode-cotton interactions if we are to be able to create new management strategies for cotton nematodes.