Assessment plays an important role in education and can both guide and motivate learning. Assessment can, however, be carried out with different aims: providing the students with feedback that supports the learning (formative assessment) and judging to which degree the students have fulfilled the intended learning outcomes (summative assessment). In this study, we explore the instructors' perspective on assessment within the context of introductory programming courses offered to non-computer-science majors at a public tuitionfree state-funded university in a Nordic country. These courses are given to a large number of students and also employ several teaching assistants (TAs). We used constructivism as a basis for our study and investigated how instructors implement formative and summative assessments, how they view their role, and what expectations they have of their TAs in these assessments. We interviewed seven course coordinators (main instructors for introductory programming courses with additional administrative duties but without formal responsibility of the grading) and analyzed 205 course artifacts, such as syllabi, lab assignment instructions, and course material from the cross-department TA training course. The results showed that course coordinators use formative and summative assessments both separately and within the same activity. They view themselves as responsible for the assessments, as the planners and material developers, as the organizers and administrators, and as monitors of the assessments. However, the results also showed that these course coordinators delegate much of the responsibility for the assessments to their TAs and expect TAs to both grade the students and provide them with feedback and guidance. In addition, the TAs are also expected to act as informants about their students' performance. The course coordinators' role entails many different aspects, where communicating through instructions to both students and TAs is essential. We see that this implementation of assessment, with lots of responsibility distributed to the TAs, could be difficult to manage for a single faculty member who is not necessarily responsible for the grading. Based on the results, we outline some recommendations, such as offering TA training.