Intervention fidelity (IF) is a relatively recent methodological consideration in nursing research that refers to the adherent and competent behaviors by the interventionist in the delivery of the intervention as planned (Santacroce, Maccarelli, & Grey, 2004; Stein, Sargent, & Rafaels, 2007). Intervention fidelity is a major contributor to the internal validity of a study. When an intervention is delivered as prescribed, the inference that the outcome is caused by the intervention is supported. If intervention fidelity is low, the expected differences between intervention group and control group may not occur. Historically, researchers have used various recording devices [audio or video tapes] to gather data on intervention fidelity. However, concerns about privacy or disruption of the intervention as a result of taping may prevent this method from being used. Field notes written at the time of the delivery may be a solution. However, field notes have not been extensively tested as an alternative device. The purpose of this pilot study was to explore an alternative method of determining intervention fidelity using chronological field notes (CFNs) (Stein, et al., 2007; Waltz, Addis, Koerner, & Jacobson, 1993). Method: A secondary analysis using data from an intervention study that used chronological field notes was completed. A randomly selected sample of chronological field notes (N=181) written by interventionist nurses (N=20) were coded using the Collaborative Study Psychotherapy Rating Scale (CSPRS), a validated fidelity instrument used in similar studies. Results: The interrater reliability (IRR) on the CSPRS was excellent on adherence (IRR .95 and Cronbach alpha .97) and for the new competence scale, IRR .74 and Cronbach alpha .91. The results on the CSPRS were comparable to a study (Hill, 1992) that used traditional methods of transcribed audiotapes. This exploratory study provided support that an alternative methodological approach to determining intervention fidelity is feasible. Further research with a larger sample is needed to conclude with greater certainty that intervention fidelity can be determined using field notes.