Correctional literature on determinants of prisoner misconduct is largely focused on the situation in the USA or West European countries. This study expands the research in this field by presenting findings from Romania, an East European country whose prison system faces severe problems, among which overcrowding and poor confinement conditions are of the utmost concern. Therefore a survey was conducted on a sample of 280 adult male inmates in four large Romanian prisons. These exceptional data were supplemented with information from official records drawn from the prison administration’s databases. A unique combination of importation and deprivation factors, with a particular focus on several prison deprivations perceived by inmates as problematic, is examined in relation to the prevalence of four types of inmate misbehaviour: total misconduct, contraband infractions, violence and defiance. The findings show a clear relationship between importation and deprivation characteristics and prison misconduct. Also a differential impact of these characteristics is shown, depending on the type of prison infraction examined. The study concludes by advancing a set of policy recommendations to reduce the incidence of institutional misconduct in Romanian prisons.