This paper investigates the intertwined evolution of librarianship and social welfare work during the Progressive Era (1900–1920) via a case study of the librarian Edith Guerrier (1870–1958). From 1898 through 1917, Guerrier worked in the immigrant community of Boston’s North End. She established a programme of girls’ reading groups that provided access to core elements of a progressive liberal arts education. The most notable of these was the Saturday Evening Girls (SEG). Concurrently, Guerrier established the Paul Revere Pottery, a retail art pottery studio run by the young women of the SEG. Using Guerrier’s varied career as a starting point, this paper explores the role of the ‘new woman’ as an agent of social change versus social control, progressive library programmes and their promotion of reading material, and issues of acculturation, cultural plurality, and personal agency among immigrant girls and young women.