This preliminary research was directed toward further understanding the fundamental science of matrix-adhesive interactions of adhesively bonded composite aircraft structure throughout the product’s lifecycle. Nanoindentation techniques were used to characterize various regions of adhesively bonded carbon fiber epoxy samples including the matrix resin, adhesive, and bondline mixing zones (interface/interphase). For this study, adhesive bonded structure from two carbon fiber parts with long-term on ground environmental exposure and in-service exposure. These parts were compared to lab produced pristine samples through nanomechanical tests to understand the differences between initial interface and/or interphase development and the adhesive interface/interphase after in-service conditions. This work is unique in that other mechanical property characterization methods have not been able to isolate the adhesive/adherend interphase due to the micron scale of these regions. These methods not only measure the adhesive/adherend interphase initial development but also allow for the evaluation of properties that may be related to bond quality and performance.