Background: This paper identifies core elements in principal definitions of elder abuse or mistreatment of older adults (EA/MOA) and discusses the relevance of four crucial concepts: age, vulnerability, trust, and power balance in relationships.

Method: A critical analysis of selected literature in EA/MOA with a focus on works from the last 10 years.

Results: Current definitions of EA/MOA share commonalities regarding an understanding of elder abuse as a status offence, the inclusion of both acts and omissions, and the consideration of multiple levels of behavior and its effects. Definitions differ with regard to aspects as crucial as the intentionality of an abusive action and its actual or potential harmful effects. EA/MOA can be considered as a complex subtype of victimization in later life limited to victim–perpetrator relationships, where the perpetrator has assumed responsibility for the victim, the victim puts trust in the offender, or the role assigned to the offending person creates the perception and expectation that the victim may trust the perpetrator. Vulnerability is identified as a key variable in EA/MOA theory and research. With regard to neglect, the mere possibility of being neglected presupposes a heightened level of vulnerability. Power imbalance often characterizes victim – perpetrator relationships but is not a necessary characteristic of abuse.

Conclusion: Research on EA/MOA needs conceptual development. Confining phenomena of EA/MOA to specific relationships and tying them to notions of vulnerability has implications for research design and sampling and points to the limits of population-based victimization surveys.