Spatial neglect (SN) is 1) the failure to report stimuli in the contra-lesional space, or 2) the lack of initiation or ineffective movement toward or within the contra-lesional space. Because patients with SN often have hemiplegia or hemiparesis, some hypothesize that asymmetrical physical impairment, rather than SN, is the leading predictor of poor rehabilitation outcome.We developed the Movement and Mobility Scale (MMS) to assess upper and lower extremities in left versus right voluntary movement and mobility. Inter-rater reliability was examined by having two physical therapists (PT) independently assessed 13 patients. With a good inter-rater reliability, kappa=.75, seven PTs were trained to use the MMS. They then assessed patients admitted with a first stroke or traumatic brain injury (TBI) within 100 days post-injury to the inpatient rehabilitation facility. All patients also received the FIM (admission and discharge) and the Catherine Bergego Scale via the Kessler Foundation Neglect Assessment Process (admission).Seventy-six patients were tested (61 with stroke; 15 with TBI). Median age was 69 years old (IQR=55–79). 43 patients (56.6%) had SN. Patients with SN had lower FIM scores at discharge than those without SN (M=71.2 vs. 89.2). Controlling for admission FIM and age, there was a significant main effect of SN, F(1,72)=19.71, P<.001. To examine the a priori hypothesis, we additionally controlled for MMS, which provided indices for asymmetrical movement in upper and lower extremities and asymmetrical mobility in left versus right space. The main effect of SN remained robust, F(1,69)=17.71, P<.001.As reported in previous studies, SN impedes rehabilitation outcome in individuals with acquired brain injury. Additionally, we confirmed that such finding cannot be attributed to asymmetrical physical abilities. SN must be addressed effectively in rehabilitation care in order to improve outcome.