Research has linked prison misconduct to reoffending and re-entry experiences, yet no studies have sought to examine the factors influencing misconduct in Northern Ireland or if these factors operate differently for separated prisoners (those claiming their offences are politically motivated and demanding to be held separately to the rest of the prison population) compared to the general prison population. This study addresses this gap by examining the characteristics related to misconduct in Northern Ireland. Using a cross-sectional sample of 892 imprisoned adult men, the findings indicate that increased involvement in misconduct is associated with multiple needs. Younger age, racial/ethnic identity, accommodation issues, addiction, impairments, property offences, previous incarceration, prison complaints, not having a drug test and engagement/suspected engagement in serious self-harm while imprisoned increased the risk of misconduct. Reporting a nationality other than British, Irish or Northern Irish, passing prison drug tests and prison visitation lowered the risk of misconduct. Factors were found to operate in a similar manner for both the general prison population and separated prisoners, with the exception of prison complaints. Given the link between misconduct and reoffending, it is argued that specialist supports are required to address the multiple needs of those who frequently engage in misconduct if efforts to reduce recidivism are to be enhanced.