Westberg promotes the use of historical perspectives and methods within the field of educational research, and has paid special attention to the history of primary schooling and early childhood care and education (ECCE). He has a particular interest in questions regarding the how's and why's of educational expansion, not the least the rise of mass schooling during the 19th century and the expansion of ECCE since the 1960s. As a result, he has published monographs, edited books, textbooks and journals articles covering issues relating to the social and economic history of education; school finance; material culture, school architecture; teachers, teachers' salary and livelihoods, discipline and governmentalities; educational borrowing and educational transfer.