Astrophysical nucleosynthesis is a family of diverse processes by which atomic nuclei undergo nuclear reactions and decays to form new nuclei. The complex nature of nucleosynthesis, which can involve as many as tens of thousands of interactions between thousands of nuclei, makes it difficult to study any one of these interactions in isolation using standard approaches. In this work, we present a new technique, nucleosynthesis tracing, that we use to quantify the specific role of individual nuclear reaction, decay, and fission processes in relationship to nucleosynthesis as a whole. We apply this technique to study fission and β − -decay as they occur in the rapid neutron capture (r) process of nucleosynthesis.