The CMMI® defines the Process Group (PG) this way:
A collection of specialists that facilitate the definition, maintenance, and improvement of the process(es) used by the organization.
Although this sort of group is required to achieve CMMI Maturity Level 3, most organizations find that it is an indispensible part of any process improvement effort, even when starting from the very beginning at Level 1.
The effectiveness of your SEPG/PG is second only to senior management support as the most important determinent of your organization's ability to make progress against the goals established by the CMMI. Most organizations find that they can not staff their SEPG/PG with players who have any significant process improvement experience, so an experienced coach is critical to their ability to make sustained progress. But even if you do have players with process improvement experience, your SEPG/PG still needs a coach.
The Coach will assure that the SEPG/PG remains focused on their goals, avoids pitfalls that stand in their way, apply their professional judgement to the critical issues, and make continued significant progress toward improving the organization's process maturity. The coach participates in the SEPG/PG planning, sits in on team meetings as needed, consults regularly with the SEPG/PG leader and the members, and reviews all plans, proposals and artifacts produced by the SEPG/PG.
ASK Process's practical experience in software engineering as well as process improvement will give your SEPG/PG the edge they need to lead your organization to process maturity.