Defining the requirements for cellular proliferation is critical for understanding organismal development and disease etiology. CRISPR/Cas9-based approaches for genome editing are revolutionizing the ability to conduct functional studies. However, at present these strategies are underutilized for the analysis of essential genes. I will describe our ongoing work to utilize CRISPR/Cas9 to generate inducible knockouts of diverse cell cycle components, and conduct tagging strategies at endogenous loci. This work has provided fundamental new insights into consequences of the acute and chronic elimination of key cell cycle players, and provides a model for extending these strategies to diverse cellular processes.