O'Reilly founded the Association for Research on Mothering (ARM) at York University in 1998 and ran it until it closed in 2010. Its disbandment led to the inception of a new organization, the Motherhood Initiative for Research and Community Involvement (MIRCI). She is founder and editor-in-chief of the Journal of the Association for Research on Mothering, now the Journal of the Motherhood Initiative for Research and Community Involvement. In 2006, as director of ARM, she founded Demeter Press, the first feminist press on motherhood. As well, she is founder of the feminist mothers group "Mother Outlaws".
She is also the author and editor of eighteen books on motherhood.
- Redefining Motherhood: Changing Identities and Patterns. (Second Story Press, 1998)
- Toni Morrison and Motherhood: A Politics of the Heart. (SUNY Press, 2004)
- From Motherhood to Mothering: The Legacy of Adrienne Rich's Of Woman Born. (SUNY Press, 2004)
- Motherhood: Power and Oppression (edited by Marie Porter, Patricia Short & Andrea O'Reilly). (Women's Press, 2005)
- Rocking the Cradle: Thoughts on Feminism, Motherhood and the Possibility of Empowered Mothering. (Demeter Press, 2006)
- Encyclopedia of Motherhood, General Editor. (Sage, 2010)
- "Motherhood association to close". CBC.ca. Archived from the original on March 10, 2010. Retrieved September 3, 2019.
- Epp Buller, Rachel (June 4, 2014). "Andrea O'Reilly: Motherhood is NOT a Liability". LiteraryMama.com. Retrieved 25 April 2015.
- "Andrea O'Reilly". us.sagepub.com. SAGE Publications Inc.
- Lindsay, Sandy (June 30, 2018). "Professor Andrea O'Reilly speaks on motherhood yesterday and today". Saugeen Times.