Tumors contain many components in addition to the cancer cells, including blood vessels, fibroblasts and immune cells. Understanding the dynamic interactions of these populations in the tumor microenvironment is an important key for understanding cancer progression. While genetic studies and tumor biopsies have generated insights, direct time lapse imaging adds much to our understanding of the importance of these stromal components. In the February issue of Cold Spring Harbor Protocols, Andrew Ewald, Zena Werb and Mikala Egeblad provide Dynamic, Long-Term In Vivo Imaging of Tumor-Stroma Interactions in Mouse Models of Breast Cancer Using Spinning-Disk Confocal Microscopy. In addition to this overview of the technique, related protocols for Preparation of Mice for Long-Term Intravital Imaging of the Mammary Gland and Monitoring of Vital Signs for Long-Term Survival of Mice Under Anesthesia are also available.