Multi-parton superstring amplitudes are of considerable theoretical interest in the framework of a full-fledged superstring theory as well as describing phenomenological aspects like corrections to four-dimensional scattering processes. Neveu-Schwarz fermions and Ramond spin fields enter string scattering amplitudes through vertex operators of bosonic and fermionic string states and determine the Lorentz structure of the total amplitude. In this thesis we provide calculational tools to evaluate correlation functions of Ramond-Neveu-Schwarz fields for tree- and loop-scattering in four, six,...