Constitutions enshrine the fundamental values of a people and they build a framework for a state’s public policy. With regard to generational change, their endurance gives rise to two interlinked concerns: the sovereignty concern and the forgone welfare concern. If constitutions are intergenerational contracts, how (in)flexible should they be? This article discusses perpetual constitutions, sunset constitutions, constitutional reform commissions and constitutional conventions, both historically and analytically. It arrives at the conclusion that very rigid constitutions are incompatible with the principle of (...) intergenerational justice. Recurring constitutional reform commissions in fixed time intervals would give each generation of citizens a say without leaning too much to the side of flexibility. (shrink)