Cowan was also a leading advocate for public education and the rights of children (particularly those born to single mothers). She was one of the first women to serve on a local board of education, and in 1906 helped to found the Children's Protection Society, whose lobbying resulted in the creation of the Children's Court the following year. Cowan was a co-founder of the Women's Service Guild in 1909, and in 1911 helped establish a state branch of the National Council of Women.