You've seen it happen. A team that started as a unified group gradually splits into camps. The engineers huddle together at lunch. The veterans share knowing glances when new hires speak up. The remote workers form their own chat channel that somehow never includes the office-based staff.

These divisions feel natural, even inevitable. And in some ways, they are. Humans are tribal creatures, and we instinctively seek out those who feel familiar. But when these natural clustering tendencies go unchecked, they can transform a team into a collection of competing factions—each with its own agenda, its own information streams, its own version of reality.

Understanding how subgroups form isn't just academic curiosity. It's essential knowledge for anyone trying to build a team that actually functions as one. The good news: these patterns are predictable. And predictable means manageable.

Every team develops informal structures that exist alongside the official org chart. These coalitions aren't inherently destructive—they often serve real functions, like providing psychological safety or streamlining communication. The problem emerges when they calcify into rigid boundaries.

Coalition formation follows predictable psychological drivers. Similarity attraction pulls us toward people who share our backgrounds, working styles, or perspectives. Proximity effects mean those who sit near each other or share schedules naturally bond. Shared history creates in-groups among people who've weathered challenges together.

The most insidious driver is often uncertainty reduction. When organizational direction feels unclear, people seek allies who can help them interpret what's happening. These interpretation communities become echo chambers, each developing its own narrative about the team's situation.

Watch for the early signs: consistent seating patterns in meetings, private communication channels, language that distinguishes 'us' from 'them' within the same team. Coalition formation accelerates during times of stress or change—precisely when team cohesion matters most.

Takeaway

Coalitions form fastest when people feel uncertain. The less clarity a team has about its direction, the more its members will seek allies to help them make sense of things—and those alliances can quickly become fault lines.

Researchers use the term 'faultlines' to describe the hypothetical dividing lines that split a group into subgroups. These aren't random—they form along attributes that align with each other. A team where all the women are also the newest hires and all work remotely has a strong faultline. A team where demographics, tenure, and location are randomly distributed has a weak one.

Strong faultlines create what psychologists call 'us versus them' cognition at the team level. Information stops flowing across the divide. Assumptions about the other subgroup's motives become increasingly uncharitable. Conflicts that should be about tasks become conflicts about identity.

The particular attributes that create faultlines depend on context. In some organizations, educational background matters enormously. In others, it's whether you came from an acquisition or were an original employee. The key insight is that any attribute can become a faultline if it aligns with other attributes to create a coherent subgroup identity.

Functional faultlines—divisions based on job roles—are especially common and especially problematic. When all the salespeople think one way and all the product people think another, debates about strategy become tribal conflicts where being right matters less than whose side wins.

Takeaway

A single difference rarely fragments a team. Fragmentation happens when multiple differences align—when the same people are always on the same side of every divide. Strong faultlines aren't just organizational inconveniences; they fundamentally change how team members perceive each other.

The goal isn't eliminating subgroups—that's neither possible nor desirable. The goal is preventing them from becoming hermetically sealed. Teams need bridgers: people who maintain genuine connections across subgroup boundaries and can translate between different perspectives.

Some bridging happens naturally. Look for team members who seem comfortable in multiple contexts, who get invited to lunch by different groups, who can explain one faction's concerns to another without distortion. These people are organizational assets worth protecting.

When natural bridging is insufficient, structural interventions help. Cross-functional projects that require genuine collaboration—not just parallel work—force new relationship formation. Rotating meeting facilitators ensures different voices shape discussions. Physical and virtual space design can either reinforce or disrupt existing patterns.

The most powerful intervention is often the simplest: create shared experiences that generate new coalitions. When team members go through something challenging together, the bonds formed can cut across existing faultlines. The key is ensuring these experiences create genuinely diverse groupings rather than reinforcing existing clusters.

Takeaway

You don't need to eliminate subgroups—you need to make their boundaries porous. Every team member who maintains real relationships across internal divides acts as a bridge, carrying information and goodwill in both directions.

Subgroup formation isn't a sign of team dysfunction—it's a sign of human nature. The question isn't whether your team will develop internal clusters, but whether those clusters will cooperate or compete.

The teams that maintain cohesion despite internal diversity share a common feature: they cultivate bridgers deliberately. They notice when faultlines are forming and intervene before those lines become walls. They create structures that force connection rather than hoping it happens organically.

Pay attention to the invisible architecture of your team. The informal alliances, the lunch table geography, the Slack channels within Slack channels. These patterns reveal where your team is strong—and where it might be starting to fragment.