Involuntary memory chains are spontaneous recollections of the past that occur as a sequence of associated memories. This memory phenomenon has provided some insights into the nature of associations in autobiographical memory. For example, it has shown that conceptually associated memories (memories sharing similar content, such as the same people or themes) are more prevalent than general-event associated memories (memories from the same extended event period, such as a trip). This finding has suggested that conceptual associations are a central organisational principle in the autobiographical memory system. This study used involuntary memories chains to gain additional insights into the associative structure of autobiographical memory. Among the main results, we found that general-event associations have higher rates of forgetting than conceptual associations, and in long memory chains (i.e., those with more than two memories) conceptually associated memories were more likely to activate memories in their associative class, whereas general-event associated memories were less likely to activate memories in their associative class. We interpret the results as further evidence that conceptual associations are a major organising principle in the autobiographical memory system, and attempt to explain why general-event associations have shorter lifespans than conceptual associations.