[2] She taught first at Loreto College, Victoria,[4] urging higher education scholarships for Catholic girls to produce 'a band of noble thoughtful women as a powerful influence for good'.

A second marriage at Christ Church, St Kilda, Melbourne on 1 October 1909 to George D'Arcie Lavender, thirty years her junior, was apparently short lived.

[2] As vice-president of the Women's Political Association in 1912 - 1914 Guerin co-authored Vida Goldstein's 1913 Senate election pamphlet, but dual membership of non-party feminist and Labor Party organizations proved untenable.

[1][2] An ardent anti-war propagandist, she led the Labor Women's Anti-Conscription Fellowship campaign during the 1916 referendum and spoke in Adelaide, Broken Hill and Victorian metropolitan and country centres against militarism and in defence of rights of assembly and free speech.

Henceforth she organized for Labor "only so far as it stands for those principles represented by the Red Flag", believing in the parliamentary system but desiring capitalism's elimination.