This CEUR volume contains the research proposals accepted for presentation at the 13th International Doctoral Symposium on Empirical Software Engineering (IDoESE 2015), held in Beijing, China, the 21st of October 2015, as an event integrated in the Empirical Software Engineering International Week (ESEIW), which remarkably included the world-leading Empirical Software Engineering and Measurement conference (ESEM 2015). The objective of the doctoral symposium is to provide junior researchers with the opportunity to present their work to the empirical software engineering community and receive valuable feedback from experienced researchers in that community. The symposium also aims at facilitating the exchange of ideas among young researchers. To do so, experienced members of the empirical software engineering community serve as symposium advisors and provide feedback to students presenting their work. This year, 6 research proposals were selected for presentation at IDoESE 2015. Each paper was subjected to reviews by three different members of the Boards of Advisors. Whenever the reviews for a paper showed any divergence, the reviewers were asked to conduct a discussion electronically with the aim of reaching a consensus. In addition, each accepted paper received an additional review from an author of other accepted paper, which provided a peer perspective to his/her work. The proposals were arranged into three sessions: Methodology and tools (chair: Marcela Genero), Costrelated studies (chair: Ayse Tosun Misirli) and Code-related studies (chair: Sergio Soares). Following the goal of fostering discussion, each paper was assigned 45 minutes, half of the time for presentation, half of the time for discussion. In the discussion slot, the student that made the review for that paper summarized his/her view, and then the board of advisors conducted the discussion. The event was completed with an exciting keynote talk given by Prof. Sira Vegas from Universidad Politécnica de Madrid (UPM) entitled “What makes a good Empirical Software Engineering Thesis?: Some Advice”. We would like to thank all the people involved in the organization of the event: the ESEM General coChairs, Quin Wang and Guenther Ruhe, who provided support and advice throughout the event organization; the Board of Advisors (see next page for the listing), who took care of the reviews and participated in the event; all the ESEIW organization team and of course all the PhD students who submitted their work for consideration to the symposium.