Abstract: Our laboratory exploits Drosophila hemocytes as an in vivo model to address the role and regulation of cell migration during animal development. These cells can be live imaged during their developmental dispersal at an unprecedented spatiotemporal resolution; this has allowed us to develop image analysis techniques to dissect the subcellular dynamics of their migratory behaviours along with their functions during embryogenesis. In this seminar I will discuss recent work that reveals the critical role of actin flows in coordinating the migratory process. Additionally, I will highlight the intriguing function that hemocytes play during Drosophila development: this macrophage population is surprisingly essential for the production and localised deposition of extracellular matrix within the embryo.