Fluorene-based pi-conjugated polymers and oligomers combine several advantageous properties that make them well-suited candidates for applications in organic optoelectronic devices and chemical sensors. This review highlights strategies to synthesize these materials and to tune their absorption and emission colors. Furthermore, methods to control their supra-molecular organization will be discussed. In many cases, a delicate interplay between the chemical structure and the processing conditions are found, resulting in a high sensitivity of both structural features and optical properties. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4215-4233, 2009