Objectives In the Netherlands, the Actuarial Risk Assessment Instrument for Youth Protection (ARIJ) is a widely used safety and risk assessment instrument in child welfare, although little is known about its reliability. Therefore, this study aimed to determine the reliability of the ARIJ by examining the inter-and intrarater reliability. Methods For determining interrater reliability, professionals of two Dutch agencies (child and family support, n = 39 & child protection, n = 24) and master students (n = 65) each rated a random selection of 4 out of 24 vignettes. The vignettes were based on actual cases that were handled by the two agencies. For determining intrarater reliability, the professionals rated four vignettes twice with an interval of at least 3 months. Three reliability measures were calculated for each of the three samples: percent agreement, Krippendorff's alpha, and Gwet's Agreement Coefficient.Results Overall, the items and outcome of the safety assessment instrument showed a moderate or higher than moderate interrater reliability, and a substantial to almost perfect intrarater reliability. In general, the risk assessment items showed a moderate interrater and a substantial-to-high intrarater reliability. The risk assessment outcome had a near perfect interrater reliability and a substantial to almost perfect intrarater reliability. Conclusions The outcome of both the safety and risk assessment of the ARIJ proved to be reliable and justifies the use of the ARIJ in the Dutch child welfare by professionals with different levels of experience.