This paper reports on the construct validity (scale design and convergent validity) and ecological validity of the Occupational Therapy Adult Perceptual Screening Test (OT-APST). The performance of 208 participants following stroke on the OT-APST and a reference tool (either the Loewenstein Occupational Therapy Cognitive Assessment (LOTCA) or the LOTCA-Geriatric version (LOTCA-G)) was compared. The OT-APST performance of the stroke sample was compared with a healthy normative sample (n = 356). The relationship between the OT-APST performance and the Functional Independence Measure (FIM) score of the participants following stroke was also examined. Factor analysis and internal consistency results supported the scale design of the OT-APST. Significant correlations between the performance of the participants following stroke on the OT-APST and the reference tool supported the convergent validity of the OT-APST. The ability of the OT-APST to separate the two participant groups provided further evidence of its construct validity. Significant correlations between OT-APST and FIM scores supported the ecological validity of this tool. This study shows that the OT-APST is an ecologically valid tool with demonstrated construct validity in the assessment of visual perception.