Objective: This study aims to define the performance of rear-facing child restraint systems (RF CRS) in moderate severity rear impacts. The study also investigates whether certain RF CRS features may mitigate or exacerbate injury risk in this scenario. Methods: Twelve tests were conducted at a moderate severity rear impact sled pulse (approximately 28.2 km/h and 18.4 g). Four different models of RF CRS were tested in the rear outboard positions of a popular compact sedan seat. The CRABI 12-month-old and Hybrid III 3-year-old anthropomorphic test devices (ATDs) were instrumented with head and chest accelerometers, head angular rate sensors, six-axis upper neck load cells, and a chest linear potentiometer (3-year-old only). The test matrix investigated the effects of carry handle position, occupant size, presence of anti-rebound bar, Swedish style tethering, and lower anchor vs. seat belt installation. Data were also analyzed for occupant injury criteria exceeding current pediatric injury assessment reference values (IARVs). Results: Head contact was prevented in seven of the twelve trials through the use of either an anti-rebound bar, Swedish style tethering, or simple interaction between the CRS base and the vehicle seat cushions. Head Injury Criterion (HIC15) values across all tests were small compared to current IARVs and US federal regulation limits, despite head contact against the vehicle head restraint and/or carry handle in five trials. Chest resultant accelerations (3ms duration) were also well below current injury thresholds. Neck loads and combined axial force and moment (Nij) varied depending on the features of the CRS, but all were below current injury thresholds. Conclusions: The results indicate that occupants of properly installed RF CRS are unlikely to suffer serious injuries in moderate severity rear impacts. This study provides experimental data to address this crash scenario, which are currently lacking in the literature. These conclusions are supported by epidemiological and field data which indicate that RF CRS provide good protection for young occupants in all crash scenarios.