Quantum Dots captures many diverse applications enabling utility in biological detection. Organized into five parts, the first two parts cover the use of QDs in imaging fixed and living cells (and tissues). Protocols are included for using QDs in routine (protein and structural cellular labeling), as well as enabling (single receptor trafficking, clinical pathology, correlative microscopy) applications. Part 3 shows early efforts aimed at using QDs in live animals. The final 2 parts demonstrate the versatility of QD technology in existing assay technology.