  As software engineering research becomes more concerned with the
psychological, sociological and managerial aspects of software development,
relevant theories from reference disciplines are increasingly important for
understanding the field's core phenomena of interest. However, the degree to
which software engineering research draws on relevant social sciences remains
unclear. This study therefore investigates the use of social science theories
in five influential software engineering journals over 13 years. It analyzes
not only the extent of theory use but also what, how and where these theories
are used. While 87 different theories are used, less than two percent of papers
use a social science theory, most theories are used in only one paper, most
social sciences are ignored, and the theories are rarely tested for
applicability to software engineering contexts. Ignoring relevant social
science theories may (1) undermine the community's ability to generate,
elaborate and maintain a cumulative body of knowledge; and (2) lead to
oversimplified models of software engineering phenomena. More attention to
theory is needed for software engineering to mature as a scientific discipline.
