Nanoparticle formulations of hydrophobic drugs present unique opportunities for treatment of solid tumor cancers, for delivery of drugs by aerosol administration. The common requirements of these applications are precise control of particle size and surface functionality. We present our new process --Flash NanoPrecipitation – a controlled precipitation process that produces stable nanoparticles at high concentrations using amphiphilic diblock copolymers to direct self-assembly. Uniform particles with tunable sizes from 50-500 nm can be prepared in an economical and scalable manner. The key to the process is the control of time scales for micromixing, polymer self-assembly, and particle nucleation and growth. The diffusion-limited assembly enables particles of complex composition to be formed. The PEG protective layer creates long-circulating particles and the inclusion of PEG chains with terminal ligands allows drug targeting. Examples of particle formation for controlled delivery of multiple drugs from nanoparticles will be presented. This enables the simultaneous, controlled release of multiple drug “cocktails” from nanoparticles for the treatment of cancers and HIV. The incorporation of gold or magnetite nanoparticles or fluorophores with drugs into a single nanoparticle enables simultaneous delivery and medical imaging.