The finding
Donald Sull, Rebecca Homkes and Charles Sull’s research, published in Harvard Business Review and drawing on a multi-year study of more than 250 companies, produced one of the more precise findings on what “siloed” actually refers to in practice. Vertical alignment — the cascade of strategy down through reporting lines — was, across the organisations they studied, generally functioning as intended. The breakdown was lateral: only 9% of managers said they could reliably rely on colleagues in other functions and units to deliver all of the time, with around half saying most of the time.
That’s a more specific claim than “the organisation is siloed” usually conveys. It isn’t that departments don’t understand the strategy, or that leadership hasn’t communicated it. It’s that the coordination between departments — the part of execution that happens laterally, across boundaries a hierarchy was never built to manage — is where the strategy most reliably comes apart.
This has a direct bearing on how the word gets used in practice. “Siloed” is frequently deployed as a criticism of a specific department’s attitude — a team accused of hoarding information or refusing to collaborate. The research points somewhere less personal: the same organisation could rotate every individual currently in those roles and, without changing anything structural, likely see the same coordination gap persist, because the gap belongs to the structure rather than to the particular people occupying it.
What it means in practice
Jay Galbraith’s research on organisation design, published in Interfaces, gives a structural account of why this happens by default rather than by mistake. His argument was that hierarchies are efficient at moving information vertically — up for decisions, down for direction — and that as the complexity or uncertainty an organisation handles increases, the amount of information that needs to move laterally, between functions, increases with it. A traditional hierarchy has no dedicated mechanism for that lateral movement. Unless something is deliberately built to carry information sideways, it either travels informally, through relationships that don’t scale, or it doesn’t travel at all.
The relationships-based version tends to work fine for a while, which is part of why the underlying structural gap goes unaddressed for so long. A handful of long-tenured people who happen to know each other across departments can quietly compensate for the missing lateral mechanism, absorbing coordination that formally has no home. The gap only becomes visible once those specific people move on, retire, or are simply spread too thin to keep covering for a structural absence that was never actually resolved, only personally bridged.
On this account, a silo isn’t a cultural defect — a department deliberately hoarding information or refusing to collaborate. It’s closer to a structural default: what a hierarchy produces when nothing has been deliberately added to compensate for what a hierarchy was never designed to do in the first place. That distinction matters, because a cultural diagnosis and a structural one point in different directions, and misreading one as the other tends to produce responses — team-building, messaging about collaboration — aimed at a problem that isn’t the one actually present.
The same pattern appears across many kinds of organisation; see Other Sectors for how it is read elsewhere.
Questions worth considering
- Where does the organisation currently rely on lateral coordination between functions to execute its strategy, and is there anything deliberately built to support that coordination, or does it depend entirely on informal relationships?
- Is a given instance of poor cross-functional cooperation better explained structurally — no mechanism exists for it — or culturally — a mechanism exists and isn’t being used?
- Given that reliable lateral coordination appears to be the exception even in well-run organisations, is the goal realistically eliminating silos, or managing the coordination gap they represent?
More on this topic: Strategy Execution.
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