As Macromolecules celebrates its 50th anniversary, we reflect on the impact of polymer chemistry and engineering on the advancement of synthetic polymer fibers. In this Perspective, we focus on two exemplary cases: (i) high performance fibers and (ii) ultrafine electrospun fibers. High performance in this context refers to fibers like Kevlar and Spectra, which emerged as a consequence of novel chemistry and processing innovations to convert synthetic polymers into fibers with exceptional specific stiffness and strength. More recently, the development of "ultrafine" (i.e., submicrometer diameter) fibers by technologies such as electrospinning has advanced dramatically, resulting in interesting, emergent structures and properties, such as surface and internal morphologies, electrical and mechanical properties, and growth applications like tissue engineering and sensors, which are subjects of current research. In both cases, challenges and opportunities exist in the development of polymer processes to advance the current state of these synthetic polymer fibers.