The influence of similarity- and causally-based relations on the organization of autobiographical events was investigated using extended strings of related event memories. These strings were elicited using an event cueing paradigm in which participants generated descriptions of memories from their life, which were then presented as cues to subsequent event memories. In Experiment 1, similarity between generated events was investigated using participants’ similarity ratings, Latent Semantic Analysis, and experimenter judgements of shared event properties. For events close together in a string, event owners’ similarity ratings were higher than non-owners’, and non-owners’ ratings were comparable to similarity calculated using LSA. In Experiment 2, the influence of causal connectivity of events on perceived event similarity was investigated using causality ratings by event owners and non-owners. Results indicated that many events cued other events based on causal relations, owners’ causal ratings were highly consistent, and the ownership advantage in Experiment 1 could in part be explained by causal connections among events. It is concluded that both event similarity and causality are important aspects of the organization of autobiographical memory