Enabling the sharing of dormant consumer knowledge, autonomous online consumer communities constitute communities of consumption practice. Drawing from the knowledge management literature, this article investigates consumer knowledge activation and accumulation dynamics in online communities within the naturalistic setting of an online forum. The netnographic study identifies different patterns of knowledge activation, giving insights into the kind of consumer knowledge that emerges in autonomous online communities. Different characteristics of online communities such as potential presence of rare knowledge, breadth of views or additive value of similar views are leveraged, to produce different types of collective knowledge. The study contributes to the online communities literature by deconstructing the dynamics of knowledge sharing and accumulation in autonomous communities; these function as communities of consumption practice and contribute to consumer empowerment through building collective knowledge from individual activations. It contributes to the consumer knowledge literature a two-level, individual and collective, characterisation of knowledge activation and accumulation.