Business Processes are critical assets of any organization; they are their core competencies. Business Processes are the fundamental ways in which a company achieves their goals. Decisions, resulting in actions, need to be made during the lifetime of a process. Business Process Management (BPM) involves designing, automating, analyzing and improving processes. Data exchanged between systems is being standardized by the eXtensible Markup Language (XML) specification. In this paper we outline the XML-based Expert System Shell (X-ESS) used to construct the rulesets for making decisions based on XML instance documents and how this functionality can be integrated into the BPM architecture. BPM technology leverages the emerging process-oriented protocols allowing inter- and intra-enterprise collaboration.