The study on the genetic studies for grain yield and other agronomic traits under water non-stressed and water stressed conditions in cowpea was carried out using five parental lines comprising three drought resistant (IT98K-628, IT99K-7-21-2-2, SAMPEA-10) and two drought susceptible genotypes (SAMPEA-8, BIU LOCAL) which were crossed to develop F1s. The F1s were advanced to F2s and backcrosses made to the two (2) parents. The eighteen generations obtained were evaluated along with a commercial check Dan'ila in Randomized Complete Block Design (RCBD) with replications at the Institute for Agricultural Research (IAR), Samaru, Zaria. Significant differences in mean performance among the parents and the F1s suggests sufficient variability across the generations for the characters studied. The three parameter model was adequate to explain variations observed in the inheritance of days to fifty percent flowering, plant height, number of seeds per plant and root length. It was however inadequate to explain the variations observed in the inheritance of days to pod maturity, pod yield per plant and hundred seed weight. For these the six parameter model of Jinks and Jones was fitted. Non-allelic gene interactions were significant for number of matured pod per plant and pod yield per plant under the two different conditions. High broad sense heritability was obtained (95%). These showed the importance of the above traits in selection. Correlation had been found to be high and significant (positive and negative). The genotypic correlation coefficients exceeded those of the corresponding phenotypic correlation coefficient for most of the character pairs indicating that the correlation were more genetic than environmental in the three sets of cowpea crosses studied, indicating; positive response, repeatable and transmit ability of these traits in selection.