Protandry in 11 stonefly (Plecoptera) species (representing five families) from Sierra Nevada (Spain) has been studied (recorded and quantified) over their flight period. All species exhibited a positive protandry coefficient (range, 0.07–0.33), indicating that no species shows proteroginy. Protandry was less pronounced in species having extended flight periods, brief flight periods, or highly concentrated flight maximums. The degree of protandry did not correlated with the degree of sexual dimorphism in size, contradicting the theoretical prediction of increased dimorphism with increased protandry.