Engineering students particularly struggle with mathematics in the first year of their university studies. A result of these difficulties are high drop-out rates among the engineering students. There are various measures to support the students in their studies such as preparatory courses or bridging courses. The contribution of this research is to investigate the impact of certain factors on engineering students' success in their first year of studies in a supportive environment which includes a preparatory course, tutorials, a bridging course and a drop-in centre. First, we ask how the students' use of support measures impact the students' success. Second, we clarify which affective, motivational and cognitive factors affect the students' success in mathematics. Our further aim is to investigate the relationships between the factors that impact students' success. We consider potential factors during the first year of studies. Our results suggest that particularly students' mathematical abilities before the first semester and a support in tutorials during the first semester account for students' success in the final exams in the first year of engineering studies.