Flow cytometry is a powerful analytical tool that is widely used throughout drug development in various capacities. With an understanding of the range of applications flow cytometry offers, it is clear why it is heavily implemented in drug discovery and development. Studies have the ability to detect the expression of cell surface and/or intracellular molecules, determine the proportion of cell types within a heterologous cell population, and analyse cell volume and size. However, the flexibility offered means goal-guided careful study design and a thorough technological understanding are required to define and inform panel selection, compensation, and gating in flow cytometry. Pirouz Daftarian at Crown Bioscience explores these requirements and highlights the need for drug developers to ensure that flow cytometry studies are purpose-driven in their design, to realise a world where patients get the right treatment at the right time.