In this chapter we go beyond the search for geoindicators and biosignatures that might point to the presence of life, with the specific aim of detecting and confirming the presence of life. First, we review the results and interpretations of the Viking mission—the only life detection experiment ever conducted on another planetary body to date. We also examine the claim of fossilized life in the Martian meteorite ALH84001, which is instructive for the problematic issue of what evidence constitutes a positive detection of extraterrestrial life. Finally, we will provide a brief overview on the development of current life detection methods and their likely implementation.