Cotton varieties vary significantly in their tolerances to seedling diseases and nematodes and this paper examines several commercial San Joaquin Valley Acala varieties and selected experimental lines for their reactions to these pests. Results with Acala NemX, a newly released Acala variety, and experimental lines N-901 and N-903 are presented for their significant seedling disease survival potentials and for their root-knot nematode tolerance. Acala's Maxxa, Royale, and Prema have demonstrated a tolerance to Pythium ultumum seedling disease, but Maxxa's performance in seedling survival decreases when nematodes are present. Evidence suggests that nematodes may aggravate some seedling diseases and nematode tolerance improves a variety's tolerance to these diseases. The reaction of these lines in soils where seedling diseases, fusarium wilt, and root-knot nematodes are present demonstrate the value of selecting for increased tolerances to all three problems in cotton breeding programs. Cotton lint yields showed how, when acting in concert, fusarium-wilt, root-knot nematodes, and seedling diseases can exacerbate the combined effects of these diseases and pests.