Unlike the Chorus in Agamemnon, the first part of the Oresteia trilogy, who were a bunch of weather-beaten old citizens of Argos, the Chorus of Libation Bearers is made up (a) of women, and (b) women who are slaves – i.e., foreigners. This makes for some interesting contrast between the two plays. Whereas the Chorus of Agamemnon can be counted on to provide insight into the distant past, based on their knowledge from long residence in their homeland, the Chorus of Libation Bearers is relied on more for events in recent memory, like the dream of Clytemnestra from before the play begins.
The Chorus in Libation Bearers plays a much more active role in the drama than the one in Agamemnon does. Not only do they offer strong encouragement to Electra and Orestes but, at the decisive moment, they convince the Nurse to bend her message to Aegisthus: she is to tell him to leave his bodyguards at home when he comes to interrogate the two "strangers" who have just arrived at the palace. As it turns out, this is crucial in giving Orestes the opportunity to take down Aegisthus, the first step in the revenge that ends with the take-down of Clytemnestra.