Throughout the history of Software Engineering (SE) it has been repeatedly found that the humans involved, i.e. the engineers and developers in addition to other stakeholders, are a key factor in determining project outcomes and success. However, the amount of research that focuses on human aspects has been limited compared to research with technology or process focus. With increasing maturity of the field, interest in agile methods and a growing dissatisfaction with the continued challenges of developing high-quality software on time, the amount of SE research putting human aspect in primary focus has increased. In this paper we argue that a synthesized view of the emerging human-focused SE research is needed and can add value through giving focus, direction and help identify gaps. Taking cues from the addition of Behavioral Economics as an important part of the area of Economics we propose the term Behavioral Software Engineering (BSE) as an umbrella concept for research that focus on behavioral and social aspects in the work activities of software engineers. We propose that a model based on three units of analysis can give structure and point to concepts that are important for BSE. To add detail to this model we are conducting a systematic review to map out what is currently known. To exemplify the model and the area we here present the results from a subset of the identified concepts.