Background: Impaired community functioning and functional ability are common among people with schizophrenia spectrum disorders (SSD). However, changes occurring in activities of daily life (ADL) ability through interventions provided at clinical settings have not been systematically examined in this population. Methods: We retrospectively collated and analysed changes in ADL ability between admissions and discharges, measured utilising the Assessment of Motor and Process Skills (AMPS), among 72 people with SSD at a public inpatient treatment and rehabilitation facility in Western Australia. Clinical and demographic factors moderating the changes were also determined. Results: The standardised AMPS motor (p = 0.0088) and process scores (p < 0.0001) improved significantly between admission and discharge. However, overall, the improvements were of small to moderate magnitude, and >60% of participants did not experience significant or meaningful changes. Furthermore, mild to moderate impairment in the AMPS standardised motor (−1.3 SD), and process (−1.6 SD) ability was present at discharge. A logistic regression analysis revealed that low admission AMPS scores and duration of illness of more than five years predicted improvement of the AMPS motor score by discharge, but only the former predicted changes in the process scores. Other demographic, clinical, and treatment-related variables did not affect the outcome of the AMPS scores. Conclusions: Impairment of ADL ability is recalcitrant in schizophrenia. The improvement was modest and occurred only in a proportion of participants. However, promisingly, chronic illness, low baseline ADL ability, treatment with clozapine and presence of treatment-resistant schizophrenia did not have an adverse effect on the outcome.