The Southern root-knot nematode (RKN), Meloidogyne incognita (Kofoid and White) Chit., race 3 is the most important worldwide nematode pest on cotton. This study evaluated progress for increased RKN resistance from mass selection of two F₂ populations of cotton. The two populations, PD-3-14 x M-75 RNR and PD 5363 x M-75 RNR (resistant parent), were grown in a field naturally infested with RKN during the 1995 (F₂) and 1996 (F₃) cotton growing seasons. Remnant seed of F₂ and F₃ individual plants were preserved in a cold room to represent C₀ (cycle zero) and C_1, respectively. Host-plant resistance was evaluated in the field using galling indices. In the F₂ generation 96 and 92% respectively, of the populations PD-3-14 x M-75 RNR and PD 5363 x M-75 RNR had galling indices of 2.5 or less. Ninety-two and 78% of F₃ plants rated 2.5 or less for the PD-3-14 x M-75 RNR and PD 5363 x M-75 RNR crosses, respectively. Standard-unit heritability estimated by the correlation between galling score of F₂ plants and the mean galling score of F₃ progeny were -0.12 and 0.15 for the populations PD-3-14 x M-75 RNR and PD 5363 x M-75 RNR, respectively. Since response to selection is partially dependent on the heritability of RKN resistance, the PD-3-14 x M-75 RNR population was eliminated from further analysis due to a negative heritability estimate.