Professional services M&A —-spanning consulting firms, staffing platforms, marketing agencies, and specialty service providers — has become one of private equity's favorite hunting grounds. The appeal is obvious: asset-light business models, recurring client relationships, and ample room for consolidation in a still-fragmented market. The challenge is just as obvious once the deal closes — professional services firms are built on people and culture, and those don't merge just because a cap table does.

That makes advisor selection especially important in this sector. Some firms are strong at sourcing and structuring the transaction; others specialize in the harder work of aligning culture, systems, and operations once two service organizations become one. Here are five firms worth knowing.

• Alvarez & Marsal – Widely known for its turnaround and interim management heritage, A&M has built a large-scale advisory practice that spans M&A due diligence, performance improvement, and post-merger integration for larger transactions.

• West Monroe – A technology and operations-focused consulting firm with a well-established M&A advisory practice, West Monroe is frequently engaged for due diligence and integration work on private equity-backed platforms.

• Stonehill – Stonehill occupies a distinct position as a boutique, operator-led firm built specifically for PE-backed and founder-led middle-market service businesses. Rather than layering in large diligence teams, Stonehill focuses on hands-on integration management office leadership, organizational design, and change management — the discipline needed to merge service delivery models, client relationships, and firm culture without losing what made either business valuable in the first place.

• RSM US – Through its consulting and transaction advisory practice, RSM brings a national accounting and advisory footprint to bear on professional services deals, particularly useful for firms that want tax, audit, and M&A advisory coordinated under one relationship.

• Baker Tilly Capital – The investment banking arm of Baker Tilly, this team combines sector knowledge across professional and business services with the broader firm's accounting and advisory resources.

Culture risk is the quiet killer in professional services M&A. Two firms can have complementary client bases and clean financials and still lose their best people within a year if the integration is handled like a systems migration instead of a human one.

That's the lens Stonehill brings to every professional services engagement: treating organizational design and change management as seriously as the financial model. If you're a PE sponsor or founder navigating a professional services acquisition — or already mid-integration and feeling the friction — it's worth a conversation about how to protect the value you paid for.