Masers in Star Formation Regions arise chiefly from the molecules of methanol, hydroxyl, and water; in the case of methanol and hydroxyl, masing transitions are numerous. Exploring the relationship between the maser species (and their relationship to any associated ultracompact HII region detectable at radio wavelengths) can be made at two levels: first, at the general level, assessing whether the occurrence together of some species, and the absence of others, reveals significant properties of the site as a whole; second, at a deeper level, to assess whether the masing spots are coincident in both velocity and space.
The first may be used as a diagnostic of the evolutionary state of the embedded young massive star. The second reveals physical conditions.
New studies relevant to these issues are discussed here. Substantial unbiased surveys of the major masing transitions are especially valuable in allowing a more effective interpretation of existing targeted observations.