Development outcomes come in ‘clusters’ that seem difficult to exit. Typically juxtapositioned are states that are both weak in the sense of lacking fiscal resources, but also patrimonial or clientelistic in the way in which they operate. We document the individual behaviour underlying such a cluster using original data from Colombia. We show that tax evasion, as a measure of state weakness, and vote buying, as a measure of clientelism, are highly correlated at the individual level. We argue that while state weakness creates the right environment for clientelism to flourish, clientelism sets in place a structure of incentives for politicians and citizens that is detrimental to building state capacity. We also document that both practices are widely accepted in society, a result consistent with a deeply entrenched relationship of mutually reinforcing influences. Finally, we present evidence of a vector of other types of behaviour and beliefs that are highly correlated with both clientelism and tax evasion, which suggest the presence of multiple feedback loops that we argue justifies calling this situation a trap.