FSSP may refer to: Families of structurally similar proteins, a protein structures database Federal Bailiffs Service (Russia), abbreviated FSSP in Russian Firing squad synchronization problem, a problem in computer science and cellular automata Frances Slocum State Park, a state park in Luzerne County, Pennsylvania Priestly Fraternity of Saint Peter, a society of traditionalist Catholic priests and seminarians Fresh Start Schools Programme, a programme for schools in South Africa Forward Scattering Spectrometer Probe, a class of optical instruments designed to measure size and concentration of particles suspended in the air (such as cloud droplets)