Clinician-rated symptom scales are the current standard for outcome measures in Schizophrenia Spectrum Disorders (SSD) research. There has been growing interest in the development of self-report measures for people with SSD to support measurement-based care and inclusive research. We developed the Inspire Self Report Scale (ISRS), which measures the current magnitude of well-being, mood symptoms, psychosis, negative symptoms and cognition using 10 questions on a Likert or Visual analogue scale (VAS). We then investigated the correlation and concordance between patient self-report and clinician ratings on the ISRS during a clinical encounter. When ratings were discordant, we sought to identify whether the participant’s or psychiatrist’s rating was more accurate. The results indicated a moderately strong statistically significant correlation between participant and clinician ratings. When the results were discordant, the participant ratings were assessed to be more accurate than the clinician rating over 70% of the time. Clinicians reported that discussion of ratings on the ISRS gave them greater understanding of the participant’s experience. The ISRS has distinct utility compared to existing scales due to the measurement of present symptom severity, capturing multiple clinical domains, and time efficiency and ease of use. Thus, it may be useful in clinical and research settings.