There is a growing consensus in Ecological Economics that consumer preferences are neither fixed nor given, but rather endogenously determined by socio-economic and institutional factors. Hence, policy may promote green preferences directly. Yet any intervention in processes of preference formation seems to conflict with widely held liberal intuitions, imperfectly represented by the principle of Consumer Sovereignty (CS). We argue that a suitably refined, dynamic version of CS may not stand in the way of certain preferenceshaping policies. By exploring different modes of consumer learning that imply varying degrees of behavioral lock-in, we show that there is a scope for policies that influence preference formation without violating CS. This extends the range of normatively acceptable sustainability policies.