The addition of nanoreinforcements, such as carbon nanofibers (CNFs), to polymer matrix materials has been shown to significantly enhance the overall elastic properties of the resulting material. One of the challenging issues in using these advanced materials in industrial design applications is the accurate modeling of their mechanical responses. These notes are intended as a short introduction to the existing micromechanical modeling approaches for capturing the effect of CNFs in polymer materials while considering the variable properties in the CNF–matrix interphase region and waviness of the nanofibers in CNF/thermoset polymer composites.