A Professional Congress Organiser (PCO) is a common term in Europe to describe a professional congress organiser - a supplier providing meeting planning and meeting management services.
The term refers to companies that are specialized in the organisation and management of congresses, conferences, seminars and similar events.

PCOs act as consultants to a professional association's, private or public organisation's or other entity's organising committee, enacting its decisions whilst providing full service management, including but not limited to congress design, registration, site and venue selection and booking, audiovisuals, IT support, logistics, leisure management, marketing, printing and web services, sourcing speakers, funding and sponsorship, financial management and budget control, research, etc.