Earth-based observations of comets far surpass the ability of in situ observations to understand the range of cometary properties and thus provide unique insight into the relationship between comets and the formation of the solar system. Recent developments in composition have emphasized near-IR and mm-wave data, although optical and ultraviolet data still play crucial roles. Observers now realize the importance of chemistry in the coma. Surveys of nuclear sizes are beginning to provide a real size distribution and we have recent examples of breakup that provide important information on structure.