This paper examines the determinants of mathematics performance of first-year students enrolled in several business administration and economics study programmes at the beginning of the first semester (T1) and nine weeks later (T2). A simple model of educational production, which is developed in accordance with the model of Schrader and Helmke (2015), is used as the theoretical basis for our analysis. As predictors, we choose numerous variables which represent study-specific, socio-economic and biographical, motivational and cognitive aspects as well as variables that reflect the learning behaviour, working habits and the use of voluntary support (e.g., tutorials). Data from two skills tests and two surveys that were carried out at the University of Kassel in the winter semester 2011/12 and regression techniques are used to identify the determinants of mathematics performance. It turns out that the type of school graduation, final school grades, pre-knowledge and self-belief are essential determinants.