The events commemorated by memorial museums tend to involve mostly civilian victims who died under "morally problematic circumstances" that cannot easily be interpreted as heroic.
There are frequently unresolved issues concerning the identity, culpability, and punishment of the perpetrators of these killings and memorial museums often play an active research role aimed at benefiting both the victims and those prosecuting the perpetrators.
Although the concept of a memorial museum is largely a product of the 20th century, there are museums of this type that focus on events from other periods, an example being the House of Slaves (Maisons des Esclaves) in Senegal which was declared a UNESCO World Heritage Site in 1978 and acts as a museum and memorial to the Atlantic slave trade.
Memorial museums also often have close connections with, and advocate for, a specific clientele who have a special relationship to the event or its victims, such as family members or survivors, and regularly hold politically significant special events.
The following mission statement of the United States Holocaust Memorial Museum is typical in its focus on commemoration, education and advocacy: "The museum's primary mission is to advance and disseminate knowledge about this unprecedented tragedy; to preserve the memory of those who suffered; and to encourage its visitors to reflect upon the moral and spiritual questions raised by the events of the Holocaust as well as their own responsibilities as citizens of a democracy.