Psychometric properties on a newly developed Supervisor Principle Ethics Scale (SPES) are reported. The SPES was created to measure supervisees' perceptions of supervisors' use of ethical principles (Autonomy, Beneficence/Nonmaleficence, Justice, Veracity, Fidelity). Participants were vocational rehabilitation counsellors with a state agency in the United States (US) (Males = 38, Females = 49). They completed the SPES and the Supervisory Working Alliance-Trainee Form (Efstation, Patton, & Kardash, 1990). The five factors of the SPES were significantly correlated with the Supervisory Working Alliance-Trainee Form (SWAI-T), suggesting evidence of construct validity. Potential uses for the SPES in research and training activities are discussed.