Purely organic materials showing solid state room temperature phosphorescence (RTP) are receiving an ever growing interest due to their low toxicity, cost and environmental load with respect to their organometallic counterparts. In addition, specific features potentially associated with organic phosphorescent materials, such as long afterglow lifetimes, have opened the way to new possible applications including low-cost anti-counterfeiting technologies, temperature monitoring, sensing and bio-imaging. RTP of organic molecules is here reviewed for the cases where intermolecular interactions among one-type only molecules are involved. In particular, the selection is focused on papers regarding self-interactions of halogen bonding (XB) and π-π type. After recalling a few basic concepts underlying emission phenomena, a selection of examples where XB and π-π interactions are involved, separately or in conjunction, is reported. In the cases where different interpretations have been given for the same class of molecules, we have gathered and discussed the different suggested mechanisms.