The Narrowing Beam-Walking Test (NBWT) is a performance-based clinical test designed to assess balance ability in ambulatory individuals with lower-limb impairments who may be at risk for falls (e.g. lower-limb prosthesis users). Its design facilitates an assessment of balance ability with minimal subjective interpretation (i.e. participants are either on or off the beam), while the increasing level of difficulty (i.e. decreasing beam width), renders it suitable for a broad range of ability levels and possible applications. The test requires participants to walk along a set of four beams, each narrower than the last. Further distances walked on the NBWT indicate greater balance ability and reduced fall risk.