The Hybrid III dummy is the anthropomorphic test device specified in the federal regulation for occupant protection in frontal impacts. Performance requirements for the Hybrid III neck are defined in Part 572E of the Code of Federal Regulations, based on biomechanical research and development by General Motors. Compliance requires meeting specified corridors for the input to the system and the response of the system.In 1991 and 1992, a collaborative test effort was undertaken by a Task Group of the Dummy Testing Equipment Subcommittee of the SAE Human Biomechanics and Simulation Standards Committee. Ten dummy calibration laboratories participated in this effort. The Hybrid III neck flexion test, as specified by Part 572E, was the focus of this investigation.During the design and execution of these neck round-robin tests, it was found that test results were sensitive to many parameters (e.g., test apparatus physical characteristics; Hexcel® crush properties, mounting, and precrush; pendulum impact velocity; and measurement techniques). An attempt was made to control as many of these parameters as possible.In this paper, the Task Group presents the Hybrid III dummy neck round-robin test results, and addresses: repeatability within each laboratory, reproducibility between different laboratories, whether sensitive test parameters are sufficiently prescribed by Part 572E, and whether test input and response specifications provide appropriate assessments of neck performance. Overall, the neck round-robin test effort provided valuable insight to participating laboratories. Based upon the Task Group's experience, sensitive test parameters were identified and suggestions proposed to better specify these parameters in order to reduce within-laboratory and between-laboratory variations. Parameters were also identified that were not significant sources of variations. Improvements in test apparatus and procedures were made by many laboratories from information gained in this collaborative effort. Alternatives to Part 572E pendulum behavior and neck response specifications have been proposed.