The f-f emissions of lanthanide-ion complexes have predictable emission energies and many practical applications, but the emitting states are generally impervious to the surroundings. This investigation explores ligandand metal-centered emission processes for a series of mixed-ligand complexes of composition M(X-T) (NO3),, where the metal ion is europium, gadolinium, terbium, or lutetium, and X-T denotes the tridentate ligand 2,2':6',2 ''-terpyridine (H-T), 4'-phenyl-2,2':6',2 ''-terpyridine (Ph-T), or 4'-pyrrolidin-N-yl-2,2':6',2 ''-terpyridine (pyrr-T). The presence of the pyrrolidinyl substituent imparts intraligand charge-transfer (ILCT) character to the ligand-based excited states and reduces the energy gap between the singlet and the triplet excited states. An enhanced rate of intersystem crossing results in a lutetium complex with a relatively small fluorescence quantum yield (0.15%) and a gadolinium complex with an impressive phosphorescence yield of 9.6% in deaerated solution. The Tb(pyrr-T)(NO3)3 system is unique because the relatively low-energy triplet ILCT state equilibrates with the emissive f-f state. The result is a truly remarkable f-f emission signal that is sensitive to the polarity of the local environment as well as the presence of dioxygen.