Nanoscale coordination polymer nanoparticles for the co-delivery of multiple therapeutic agents are described. The multiple therapeutic agents can include a combination of different chemotherapeutic agents, a combination of one or more chemotherapeutic agents and one or more nucleic acids, such as small interfering RNA (siRNA) or microRNA, a combination of one or more chemotherapeutic agents and a photosensitizer (i.e., for use in photodynamic therapy), or a plurality of different siRNAs. Pharmaceutical formulations including the nanoparticles, methods of using the nanoparticles to treat cancer, and methods of making the nanoparticles are also described.