There is increasing interest in protective factors for violence risk and it has been proposed that consideration of protective factors in addition to risk factors may lead to more balanced and accurate violence risk assessments. Part 1: A systematic review of the literature was conducted to explore the predictive and incremental validity of protective factors assessed using structured professional judgment (SPJ) violence risk assessment tools. Eighteen studies were identified which reported the predictive validity of protective factors for violent behaviour in adolescent and adult males using five different SPJ risk assessment tools. Overall, most studies found that protective factors were associated with the absence of violence. The evidence to support the incremental validity of protective factors (in addition to risk factors) was however less robust and most studies were identified as having a risk of bias which impacted on the potential accuracy and generalisability of the findings. Part 2: Using a pseudo-prospective design, the predictive and incremental validity of protective factors was explored using the Structured Assessment of Protective Factors (SAPROF) and Historical Clinical Risk Management-20 (HCR-20V3) guidelines in a sample of 75 male patients in a high secure forensic mental health inpatient setting. The SAPROF was associated with the absence of different types of violence within the hospital setting (with AUC values for the total SAPROF score ranging from .69 to .74). The SAPROF did not appear to significantly add to the predictive validity of the dynamic risk factors in the HCR-20V3. The Integrative Final Risk Judgment however demonstrated strong predictive validity (with AUC values for different types of violence ranging from .74 to .81) and incremental validity in the prediction of violent behaviour.