This paper deals with research of students' motivation when choosing a mentor for their final and/or diploma thesis and how students arrive at a topic for their thesis. The paper is divided into a theoretical and a research part. In the theoretical part of the work, the definitions of the final and diploma thesis are presented, and the motivation of students and the connection between motivation for choosing a mentor are described. The main part of the work is the selection of a mentor when writing the paper and the relationship between the student and the mentor and their cooperation during the writing. Student-mentor relationships should be associated with better academic performance, professional development, positive self-image, psychological well-being, and emotional adjustment. The paper also discusses the procedures for properly choosing a topic for the final thesis and the essential characteristics that a student should apply when choosing a topic. Since planning the writing of the paper is also important, the paper explains what planning the writing entails, namely: finding basic information about the topic, material conditions for the preparation of the paper, the time that should be devoted to the time required for the preparation of the paper. After the theoretical part of the paper, the research conducted is presented. The research sought to find out what influenced the students to choose a specific mentor and how they came to the chosen topic. The research was conducted through a survey that was distributed through social networks, in groups whose members are students at the University of Zadar. The sample consists of respondents, current and former students at the University of Zadar, who have worked on their final or diploma thesis in the last year (approx. year 2023/2024).