Generation mean analysis study in sponge gourd was undertaken to estimate the gene action operating in the inheritance of quantitative traits using six basic generations of two interspecific crosses, namely SATPUTIA × SG 282 and SATPUTIA × PSG 9. The F2 and backcross generations showed high genetic variance for vine length, fruit weight and fruits per vine. Additive, dominant, additive x additive, additive × dominance and dominance x dominance effects significantly influenced most of the traits. The additive effect significantly contributed to fruit length and weight in both crosses. Dominance effects were significant for almost all the traits in both crosses. Additive × dominance type of interactions contributed significantly for female bud length, ovary length, style length, node to first flower, fruit diameter, fruit weight, fruits per vine and yield per vine. Duplicate effects influenced all the traits in both the crosses except for fruit length in SAT × PSG 9. For further improvement in interspecific progenies, the pedigree method can be applied to exploit additive variance to develop improved inbreds. However, transgressive segregates can further be used to exploit the presence of dominance, additive × dominance and dominance × dominance interactions.