It is at extbook knowledge that protein photoluminescence stems from the three aromatic amino acid residues of tryptophan(Trp), tyrosine (Tyr), and phenylalanine (Phe), with predominant contributions from Trp. Recently, inspired by the intrinsic emission of nonaromatic amino acids and poly(amino acids) in concentrated solutions and solids,we revisited protein light emission using bovine serum albumin (BSA) as am odel. BSA is virtually nonemissive in dilute solutions ( 0.1 mg mL À1 ), but highly luminescent upon concentration or aggregation, showing unique concentrationenhanced emission and aggregation-induced emission (AIE) characteristics.N otably,a part from well-documented UV luminescence,b right blue emission is clearly observed. Furthermore,p ersistent room-temperature phosphorescence (p-RTP) is achieved even in the amorphous solids under ambient conditions.T his visible emission can be rationalized by the clustering-triggered emission (CTE) mechanism. These findings not only provide an in-depth understanding of the emissive properties of proteins,b ut also hold strong implications for further elucidating the basis of tissue autofluorescence.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.