The Children’s Hospital of Philadelphia Research Institute (CHOP) Proteomics Core Facility (PCF) provides a variety of protein and proteomics services for investigators at CHOP, University of Pennsylvania, and outside institutions. These services include producing and characterizing proteins, investigating protein-protein interactions, and characterizing whole proteomes. Some services are provided on a user-operated, sign-up basis, while others are performed as full-service by the dedicated facility personnel. Protein expression services include recombinant protein production in bacteria. HPLC and FPLC equipment, columns and resins are available for a variety of purification needs. Endogenous fluorescence, circular dichroism, and analytical ultracentrifugation can be used to characterize folding status of proteins and their interactions with small molecules and other proteins or nucleic acids.