The academic year at Bielefeld University is divided into two semesters
Courses in the lecture period usually run from mid-October to the end of the first or second week in February (winter semester) and from mid-April to mid/end of July (summer semester). The rest of the academic year, the so-called "Semesterferien" or "vorlesungsfreie Zeit" (mid-February to mid-April and end of July to mid-October), is usually spent on doing assignments, preparing for exams, doing internships or working in student jobs. "Orientation Weeks" or preparatory courses take place a few weeks before courses officially start, and international students should plan to arrive in Bielefeld in time to take part in these orientation weeks and courses.
Christmas holidays usually begin around the 22nd or 23rd of December and last until January the 2nd or 3rd. Courses at Bielefeld University start again in the second week of January (i.e. after January 6, a public holiday in some parts of Germany).
See dates for the upcoming years 
here.
In the last weeks of each lecture period the electronic course schedule for the next semester is
published online in the so-called
"eKVV2".
It lists each class being offered, its time, location and instructor as well as a
short description of the content and reading lists. The electronic course schedule enables students
to organize and manage their own course of studies, registering for classes and
setting up their individual study plan (according to course requirements).
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