This study contributes to the enterprise architecture (EA) methodologies by suggesting a method for eliciting architecture requirements: gathering both the current architecture information, and the development needs and requirements for the business architecture (BA) dimension in EA planning. Most of all EA dimensions, the developing of the BA requires collaboration with various non-IT stakeholders. It presents thus challenges to the IT department, or the consultancy involved in EA related efforts. The contribution of the various stakeholder groups as informants is, however, crucial to well founded EA design decisions. The suggested method takes related IS development fields as starting points. Collaborative approaches are well established in the fields of requirements engineering and business process design. However, EA specific issues remain to be explicated and incorporated to the collaboration. A BA information elicitation method (IEM) is not only a tool of the IT professional for a sound foundation for defining of the EA baseline, and developing of the requirements, but also an organizational change management vehicle. Involving stakeholders in a planned, consistent and balanced manner, it supports the establishing of collaboration routines of the IT and business stakeholder groups. The observations in a 12 month EA initiation project in a public organization are a basis for this constructive effort, where a BA elicitation method for the enterprise architecting is created. The constructed method is enhanced by evaluative comments of seven EA-experienced IT professionals.