Graphene oxide paper can be systematically modified with alkylamines in both solution- and vapor-phase, with the latter process being significantly slower. After removal of physisorbed amine, the increases in gallery spacing, physical thickness, and mass of amine-modified papers can be directly correlated to the length of the intercalated alkyl chain. While the tensile strength of the modified papers slightly decreases with increasing amine lengths, their “effective graphene oxide moduli” were essentially unchanged, suggesting that graphene oxide is the sole contributor to the stiffness of amine-modified papers.