Single-molecule methods have developed into a mature and powerful research approach that is adding new insights into many different areas within the physical and life sciences. The ability to detect and perform experiments on single molecules opens up new experimental approaches to investigating the physical world. One is no longer limited by ensemble averaging, making it possible to detect subpopulations directly, to measure dynamic processes without synchronization of the sample, to visualize rare events and to gather information over the heterogeneity of the sample. Single molecules can be detected and investigated using electrophysiological approaches, force microscopy, electron microscopy or fluorescence microscopy. Pioneering work in the fluorescence-based detection of single molecules was performed by Rotman in the 1960’s and 1970’s, where he trapped individual enzymes in microdroplets and watched the generation of the fluorescent product. Hirschfeld was the first to directly detect fluorescently labeled molecules diffusing in solution, using antibodies labeled with 80–100 fluorophores. In 1989 and 1990, individual fluorophores were detected for the first time using low-temperature optical spectroscopy, initially with absorption spectroscopy, shortly thereafter with fluorescence spectroscopy and at room temperature. Historical accounts of the development of single-molecule detection can be found in refs. [5, 6] . ChemPhysChem, European in origin but international in scope, deals with all aspects of the overlapping areas between chemistry, physics, biology, and materials science. It is co-owned by Chemistry Publishing Society Europe (ChemPubSoc Europe) and published by Wiley-VCH. Contributions in ChemPhysChem cover a wide range of topics including atmospheric science, hard and soft matter, femtochemistry, nanoscience, complex biological systems, single-molecule research, clusters, colloids, catalysis, and surface science; experimental and theoretical studies can be published. ChemPhysChem publishes short Communications and long Articles, as well as Reviews, Minireviews, Highlights, Concepts, Essays, Book Reviews, and occasionally Conference Reports. Authors can submit manuscripts to ChemPhysChem online through our homepage (see left) by clicking on “Submit an Article” and following the simple instructions.