Introduction: Process notes contain unique information concerning core elements of a psychodynamic treatment. These elements may be both conscious and unconscious for the author. One element for study is the tendency to which a therapist writes about providing either supportive or expressive interventions. This study sought to establish a method of systematically and reliably identifying the records of therapists' interventions as supportive or expressive. Methods: Three early-career clinicians were trained in the use of a process note intervention rating scale constructed specifically for this study. Quantitative statistical analyses assessed the scale's reliability and internal consistency. Results: Interrater reliability analysis determined at a p of 0.005 a Fleiss's kappa of 0.24 and an intraclass correlation coefficient of 0.264, suggesting a low but statistically significant reliability between the raters. A Cronbach's alpha of 0.67 and a McDonald's omega of 0.53 suggested questionable internal consistency. Discussion: Early-career clinicians can reliably code the manifestations of interventions in psychodynamic process notes as supportive or expressive. Future studies may improve the reliability and internal consistency of the scale, add measures of interpretation content, and evaluate these data in relation to other core elements of process notes, such as the author's emotional engagement as manifested in language measures and clinical outcome.