Previous research in the field of auxiliary verb selection in the present perfect tense has focused primarily on the Romance languages (cf. Burzio, Lois, Cortes, Centineo, Posner), Dutch (cf. Lieber and Baayen, Hoekstra and Mulder, Shannon), German (Shannon, Klein) and older Germanic languages (Shannon). These studies describe the syntax and semantics of auxiliary selection for L1 speakers within a range of theoretical frameworks. With respect to L2 speakers, there are only two studies that address the issue of auxiliary selection. Sorace investigates the acquisition of choosing the correct auxiliary in L2 learners of Italian. This study assumes, as Sorace does, that auxiliary selection is a gradient phenomenon and investigates the factors that affect auxiliary selection for L2 speakers of German as well as their decision-making strategies. Auxiliary selection in German is sensitive to the degree of transitivity of a clause (cf. Shannon, Eisenberg; Zifonun, Hoffmann and Strecker, Klein). The parameters of transitivity consist of two or more participants, aspect, punctuality, volitionality, affirmation, mode, agency, affectedness of the object and the individuation of the object (Hopper and Thompson, Rice, Shannon). A common example of this is fahren [drive], which takes its auxiliary depending on presence of a direct object or other parameters of transitivity. This paper will address auxiliary selection in four groups of L2 students of German.