High grade serous ovarian carcinoma (HGSOC) is the most lethal form of ovarian cancer and is the fifth leading cause of female death in the western world. Unlike many other cancers, few viable HGSOC screening methodologies exist. HGSOC is consequently diagnosed at an advanced stage with substantial extraovarian metastases in most cases. These late stage diagnoses have hindered discovery of screening methods due to infrequent analyses of precursor lesions and uncertainty regarding HGSOC initiation mechanisms. Both the HGSOC “cell of origin” and mutations necessary for HGSOC initiation are the subject of substantial debate. Several candidate origin tissues exist in the ovarian surface epithelium (OSE), distal fallopian tubal epithelium (TE) and stem cell subpopulation of either tissue. Mutations associated with advanced HGSOC tumors have also been identified by the Cancer Genome Atlas Research Network (TCGA). However, most HGSOC-associated mutations have not been assessed as putative cancer driver mutations or passenger mutations in several putative cells of origin. In this dissertation, I performed functional screening of random combinations of suspected HGSOC driver genes in different putative cells of origin using a lentiviral CRISPR/Cas9 library. Results support the ovarian surface epithelial stem cell (OSE-SC) theory of HGSOC initiation and suggest that most HGSOC-associated mutations are uninvolved in OSE-SC transformation. Random screening, along with in vitro and in vivo validation experiments, demonstrate that disruption of Trp53, Rb1 and/or Pten are minimal OSE-SC transformation requirements, and that a few other HGSOC-associated genes may enhance transformation via Trp53 and Rb1-related mechanisms. These results are the first published efforts to functionally test all putative drivers of HGSOC and have direct implications for production of HGSOC developmental models. Such models may be useful tools for ascertainment of novel HGSOC screening methodologies. Growth-inhibitory mutations uncovered via screening also have value as putative druggable targets. Finally, the screening methodology employed here represents a rapid means of differentiating driver and passenger mutations in any cell type for which in vitro culturing exists. It may therefore serve as an important tool for elucidation of driver mutations in other cancer types.