Adaptation in sales is common in business relationships. The purpose of this study is to understand how the buyer-seller relationship affects sellers' sales process adaptation to customers' buying processes. The results reveal how the buyer-seller relationship orientation affects sales process adaptation and its effects. The main sources of information in this qualitative inquiry are in-depth, semi-structured interviews with key informants representing a buyer-seller relationship. This study helps to shed light on how the buyer-seller relationship orientation affects sales process adaptation. The findings reveal that both the buyer and the seller have an impact on sales process adaptation. Extant research has recognized adaptation as a central aspect in relationships, while largely neglecting sales process adaptation. Thus, this study focuses on the effects of buyer-seller relationship orientation on sales process adaptation.