A method and system to control an interaction of a plurality of participants in a workflow process. The method classifies the plurality of activities as (1) first activity of the workflow process, (2) first activity of a participant in an on-going workflow process, and (3) interaction activity. A set of access control policies is generated for each type of activity. The policies include workflow initialization policy, participation policy and interaction policies. The policies determine if a requesting participant is permitted to interact with a responding participant. In addition, the system includes a policy enforcement point for receiving a request from a requesting participant, wherein the request is for activating an activity of a responding participant. The policy enforcement point forwards the request to a policy decision point where the request is evaluated based on the set of access control policies.