The efficient generation, controllable management, and on-demand migration of triplet excitons from higher-lying to lower-lying triplet excited states in organic molecules have combined to constitute the long-sought Holy Grail of room-temperature phosphorescence (RTP). However, the exciton spin-flip between well-separated singlet and triplet excited states is not allowed due to the violation of Winger's rule. To tackle this apparent contradiction, ever-increasingly complex molecular design principles have been devised to modulate both the molecular structure and/or host-guest interactions. Behind these is the control of the relative kinetics of facilitating intersystem crossing (ISC) and suppressing nonradiative processes, both of which are paramount to achieving efficient RTP. From the perspective of molecular design, introducing heteroatoms, such as N, O, P, and S, into metal/halogen-free aromatic compounds is a popular way to enhance the ISC efficiency through the introduction of n-p* states that allow for the spin-flip process to occur, following the El-Sayed rule. Most recently, Marder and co-workers demonstrated that a (s, B p )®(p, B p ) transition localized on a three-coordinate boron atom could also accelerate the ISC process. This new approach likewise relies on the El-Sayed rule to mediate state mixing and thus ISC from S 1 to T 1 . To sufficiently brighten populated triplet excitons of organic compounds, it is also necessary to weaken nonradiative energy dissipation. To date, a plethora of methods, such as engineering molecular crystals, introducing a polymer matrix, and constructing a rigid host environment, have been exploited to achieve suppressed nonradiative decay. Following these principles, many RTP luminophores have been developed showing moderate photoluminescence (PL) quantum yield (F PL ) and/or long phosphorescence lifetime (t Ph ). These compounds have been exploited in diverse applications, such as imaging, optoelectronics, nonlinear optics, and information encryption. Multiple phosphorescence from a single component is an emergent phenomenon from the radiative decay of excitons from multiple accessible triplet excited states. Compounds that show multiple phosphorescence offer a handle into the study of triplet exciton dynamics. Due to Kasha's rule, it remains a formidable challenge to enable room-temperature multiple phosphorescence and thus there have been only a few reports documenting anti-Kasha RTP in organic compounds. For example, Wu and co-workers reported that heterocyclic stilbene derivatives exhibited room-temperature dual phosphorescence originating from both the T 2 and T 1 states. This results from the relatively large energy gap (> 0.5 eV) between these two states, which inhibits the excitonic internal conversion. Room temperature dual phosphorescence has also been demonstrated in both systems where there is simultaneous emission from monomers and aggregates. Recently, T 1 conformer-regulated multiple phosphorescence has been demonstrated by us, which renders the excited-state dynamics tunable via thermal activation. However, a general principle to regulate multiple phosphorescence on demand remains elusive.