Description: The paper presents the preliminary steps leading to the development of an Observatory of Student Trajectories in the University of Lisbon (UL).The state of the art of the literature on higher education students' success/failure, both international, national (Portuguese) and internal (UL) will be presented. The Portuguese statistical data will be critically assessed, statistical lacunae identified and alternative sources of data proposed. The evaluation of the University of Lisbon will be approached on the basis of the existing external evaluation reports of the University programs, each Faculty's self-evaluation report, and interviews to pedagogical leaders. Some pedagogical and organisational strengths, weaknesses, and "good practices" of the University will be identified, and three categories of "success/failure factors" will be analysed: contextual, individual, and institutional. The paper will conclude with the presentation of the next stages of this project, which include both quantitative and qualitative approaches to the study of two related phenomena: 1) UL students' transference and withdrawal rates; 2) Multiple and long-term UL students' retention rates. Methodology: This study's main data sources are: 1) official statistical information from the Portuguese Ministry of Science and Higher Education; 2) the University of Lisbon (UL) programs' self-evaluation and external evaluation reports; 3) internal studies on 1st year UL students' insertion in the academic life and UL graduates' professional inclusion; 4) annual activity reports of the Units for employment of UL graduates and psychological support services; 5) exploratory interviews to each Faculty pedagogical leader.Our methodology will include both quantitative (descriptive statistics; variance analysis) and qualitative approaches, to identify trends in UL students' success/retention/departure data, and individual case studies to understand the reasons behind those trends.The study will be monitored by a Scientific Council formed by 11 professors and researchers of 6 UL Faculties and Institutes. Special attention will be given to inter-institutional collaboration, which means that some parts of the study will be carried out by a team located in the Rectory (accountable for the project's development), while other components will be carried out by teams in other Faculties and Institutes within the University.A web page will display our "work in progress", in order to receive comments and suggestions for improvement from people within and out of the University. Conclusions: 1. Identifying the UL main pedagogical and organisational strengths, weaknesses and "good practices" for student success.2. Characterizing the persistence/withdrawal/departure problem of the UL 1st year students and developing in-depth case studies on the theme.3. Describing the multiple and long-term retention problem in the UL and developing in-depth case studies on the theme.4. Setting up an Observatory of UL Students' Trajectories.5. Piloting and implementing intervention policies for UL students' success.