In the first years of the 21st century, there was a building boom in Spain, which triggered many corruption cases in municipalities. This paper contributes to the scarce literature on this issue by analysing the impact of socio-economic and financial factors on urban political corruption. Our sample covers the 110 Spanish largest municipalities for 2000–2009. The findings indicate that higher politicians’ salaries and more transparency are connected with lower corruption levels. In this way, we confirm theoretical assumptions that posit that municipalities where politicians have higher salaries present less corruption cases. Finally, municipal transparency should be enhanced, because it is related to lower corruption.