This study aims to integrate nanofiber reinforced nanocomposite interfaces into conventional structural composites. The project tasks are divided into three parts. The first part of the study focuses on an in-situ, thermaly stimulated cross-linking strategy. It enables continous electrospinning without any viscosity problems and preserves the formed nanofibrous structures during composite making thermal cycles. Epoxy compatible polisytrene-co-glycidyl methacrylate (P(St-co-GMA)) based nanofiber production process is exemplified.. As suitable cross-linking agent and reaction initiator Phthalic Anhyride (PA) and tributyl amine (TBA) in different portions are added to P(St-co-GMA) solution. As a significant output, the nanofiber recipe along with the thermal process adopted to the composite curing cycle is presented. In the second part of the project, this recipe and thermal stimulation is implemented in in-situ cross-linking nanofiber reinforced epoxy nanocomposite manufacturing. Nanofibrous polymeric nanocomposites and their mechanical behaviour are demonstrated by mechanical testing. Performance changes by incorporation and several choices of nanofibers are reported. The efforts incude the back-calculation of the mechanical properties of the in-situ cross-linked nanofibers using DIGIMAT software. These analyses and comparative study reveal the mechanical advantages of proposed thermally stimluated chemical cross-linking. The final part of the project is dedicated to the integration of the nanofibrous interlayers into high performance structural composites. Extensive mechanical testing program is followed to characterize and demostrate the use of nanofibrous interlayers: strength parameters testing, 3-point flexural testing, fracture toughness testing, and tensile testing on custom designed lay-ups for resistance to transverse matrix cracking. Without notable weight penalty, there is %80 and %10 improvement on the mode II fracture toughness and matrix cracking failure modes, respectively. Damage tolarance capabilities of the interlayered composites are also reported by open-hole static tension and fatigue testing. Finally, the nanofibrous interlayer concept in an application problem is presented. Structural response of the small cantilever stabilizing-wing made of nanofibrous interlayered carbon/epoxy composite laminate is demonstrated as improved by %15. The reported high performance output by the project facilitates prototype of the nanofibrous interlayer integrated prepreg system