Horizontal organization is the principle that a group’s internal structure should not reproduce the hierarchies it opposes. Decision-making power distributes across all participants rather than concentrating in leaders, executives, or permanent committees.
Horizontalism is not the same as leaderlessness or structurelessness. Jo Freeman’s “The Tyranny of Structurelessness” (1972) identified the problem precisely: groups that claim to have no structure develop informal hierarchies that are harder to challenge because they are never acknowledged. Horizontal organization responds to this by making structure explicit — roles rotate, mandates are specific and temporary, processes are transparent — while refusing to arrange that structure vertically.
The term horizontalidad gained currency through the Argentine movements of 2001, when neighborhood assemblies, recovered factories, and barter networks organized without parties or unions directing them. Marina Sitrin documented these practices and the term’s development. The concept also describes Indigenous governance traditions that predate European anarchism by millennia — many Indigenous nations organized through council systems, consensus processes, and distributed authority long before anyone named the principle.
Horizontal organization connects to federation as its coordination mechanism: autonomous horizontal groups federate to act at larger scales without creating a vertical layer above them.