This paper examines the structural and functional links between symmetrical voice systems, typologically unusual and characteristic of western Austronesian languages, and systems of accusative alignment. It compares the clausal patterns of two closely related languages, Äiwoo and Engdewu, where one is analysed as having symmetrical voice and the other as having accusative alignment. It argues that the usage patterns in Äiwoo point towards a possible path of reanalysis from one type of system to another, and that this involves two key factors: increased importance of referentiality of the patient argument as a condition for the choice between two alternative constructions, and loss of the distinction between subject and nonsubject actors in two domains of grammar. Referentiality in particular, being a key factor in the concept of transitivity as it is understood in the typological literature, provides a promising avenue for better understanding the relationships between the two types of system.