Miniaturization has long been a trend in the creation of better de-vices, and the study of alternative materials for the production of well-known devices forms one large fraction of material science. Lasers and semiconductor devices have both had their part in the shaping of our current technological age and have formed a symbiosis in semi-conductor lasers. The omnipresence of these unique light sources and the remaining high cost and ecological impact of growing suitable semiconductor materials have sparked the study of organic semi-conductor devices and among them organic semiconductor lasers (OSLs). Still a field of great research efforts, the concept of micro-cavities as base structure for such systems holds the promise of in-expensive, organic or "plastic" semiconductor lasers available to the ever-growing markets of consumer electronics. Studied since the mid-90s, first organic microcavity lasers had largely inaccessible dynamics until femtosecond spectroscopic techniques became increasingly available. This book presents a study of one exemplary system, its dynamics and coherent properties. Also, introductory chapters allow greater access to the field of organic microcavities.