The intention of this paper is to make the case that personality theory is not only a legitimate, but also an essential component of empirical theology. The case is made in two parts, by drawing on theological tradition and by drawing on social scientific perspectives. The case is then illustrated by examples from one recent study in empirical theology, known as the 'pastoral care survey'. First, however, it is necessary to rehearse the nature of empirical theology, by drawing attention to the two roots of this activity in practical theology and in the pioneering work of Johannes van der Ven in the University of Nijmegen. The intention of this paper is to make the case that personality theory is not only a legitimate, but also an essential component of empirical theology. The case is made in two parts, by drawing on theological tradition and by drawing on social scientific perspectives. The case is then illustrated by examples from one recent study in empirical theology, known as the 'pastoral care survey'. First, however, it is necessary to rehearse the nature of empirical theology, by drawing attention to the two roots of this activity in practical theology and in the pioneering work of Johannes van der Ven in the University of Nijmegen.