Irish rebel songs afford Scotland’s Irish diaspora a means to assert, experience, and perform their alterity free from the complexities of the Irish language. Yet this benign intent can be offset by how the music is perceived by elements of Scotland’s majority Protestant population. The Scottish Government’s Offensive Behaviour Act (2012) has been used to prosecute those singing Irish rebel songs and there is continuing debate as to how this alleged offence should be dealt with. This article explores the social function and cultural perception of Irish rebel songs in the west coast of Scotland, examining what qualities lead to a song being perceived as ‘sectarian’, by focusing on song lyrics, performance context, and extra-musical discourse. The article explores the practice of lyrical ‘add-ins’ that inflect the meaning of key songs, and argues that the sectarianism of a song resides, at least in part, in the perception of the listener.