The New Agency Model: Horizontal Specialists vs. Vertical Generalists

The traditional full-service agency model—a single organization that handles strategy, creative, media, production, and measurement for a client—is under structural pressure from a direction that its defenders rarely acknowledge: from below. The challenge is not from rival full-service agencies or from in-house agencies. It is from specialist shops that have organized around specific capabilities—social media production, CTV buying, influencer marketing, performance creative, retail media—and can deliver in those areas with expertise and efficiency that generalist departments within large agencies cannot match. The holding companies have responded with various attempts to create specialist capability within their structures. The dedicated studios, practice groups, and centers of excellence that proliferated across WPP, Publicis, and Omnicom in 2024 and 2025 represent this response. The results have been mixed. Specialist capability within a generalist structure tends to attract the best practitioners only temporarily, because the career paths, compensation structures, and cultural environments of large full-service agencies are not well suited to deep specialists. The counter-model that is gaining traction is the horizontal specialist network: a group of independent specialist shops that can collaborate on large client engagements without being owned by a common parent. The client gets specialist expertise in each discipline without the coordination overhead and margin markup of a full-service holding company. Several large advertisers have moved to this model in the past two years, with mixed results. The coordination challenge is real. When five specialist shops are working on an integrated brief, someone has to own integration—the strategic coherence, the brief translation, the timeline management. If the client owns that integration function internally, it works. If no one owns it, the specialist model produces fragmented output. The agency model debate is not new. What is new is the capability gap between specialists and generalists in specific disciplines, and the client sophistication to understand and demand the difference.