University training requires a writing task of considerable significance, which is placed by the end of the preparation program: the thesis writing process. Both teachers' and students' representations on this task are the result of their own social experiences and expectations. This paper aims at unravelling the representations held by a group of teachers and students from two undergraduate programs in Marine Sciences, regarding the 'thesis' genre. The focus group technique was applied to six university teachers to later conduct. Then, as part of the theoretical sampling, three in-depth interviews were done on three thesis supervisors and three students who have already done their thesis. The data was analyzed following the principles of the Grounded Theory (GT) methodology. The collected information reports on how teachers and students represent the thesis writing process, what relationship exists between this representation and the steps for scientific research, and what social function thesis writing process plays in the academic community. The results reveal the different beliefs that the group of teachers and of students hold about the thesis writing process. The former, as well as thesis supervisors, represents the thesis writing task as a chain link that must be realized as a publishing scientific paper that favours their entrance to postgraduate studies. The latter, in turn, perceives the thesis writing process as a hard task to be developed, for which students feel they were not sufficiently trained to deal with. The different representations seem to be based on different assumptions: the thesis process as a means to close their period of academic training and have access to the job market and the thesis process as a means to have access to postgraduate studies and, therefore, be part of the corresponding scientific community.