This paper reports on a study, conducted in Bochum, Germany, involving 160 participants. Two research interests were combined in our study. The first aim was to integrate habit into the process of normative decision making to predict environmentally relevant behavior. Two approaches of implementing habits are analyzed and discussed. Both conceptualizing habitual and normative influences on behavior as excluding paths and integrating habit into the process of normative decision making are illustrated by data. With our approach, we intended to initialize a discussion about the consideration of habits in the context of normative decisions. The second aim was to develop and test different modifications of Verplanken's (Verplanken, Aarts, van Knippenberg, & van Knippenberg, 1994) response frequency measure (RFM) to improve the operational ization of habit. The modified forms of RFM were not more appropriate than the unmodified form. Therefore, we suggest using the unmodified RFM until there is an improved form available.