Experimental results on the gas-phase formation of neutral and cationic phosphorus clusters are presented. The clusters were synthesized by visible (532 nm) or UV (193 nm) laser ablation of crystalline red phosphorus under high vacuum conditions and were analyzed using TOF mass spectrometry. Neutral Pn clusters produced by 532-nm ablation are found to be even-numbered while Pn+ cations are mainly odd-numbered, with P7+ and P21+ being the most abundant ions. For UV laser ablation, stable compound clusters, neutral P7H3 and P23H5, and cations P23H6+ were synthesized for the first time. The formation of Pn clusters by thermal vaporization of red phosphorus into a cold He gas was also investigated and only small clusters (n ≤ 6) were found. Possible structures of the observed phosphorus clusters, as well as their formation mechanisms under different conditions, are discussed.