Certain applications of supramolecular porphyrinic systems, such as molecular sieves and photonics, rely on precise nanoarchitectural control of the molecules and/or atoms; therefore they require self-assembled systems of discrete arrays and highly ordered crystals. Other applications, such as oxidation catalysts for simple substrates, may be affected by the use of self-organized materials with less supramolecular order. Porphyrin nanoparticles can be considered self-organized systems that are governed by the principles of supramolecular chemistry. The formation and potential applications of nanoparticles of these chromophores will be discussed with special emphasis on the parameters in the methods used to make these materials, and in terms of the supramolecular chemistry. These principles, concepts, and methodologies are applicable to a wide variety of organic dyes. The advantages of self-organizing particles over self-assembled entities arise from the use of commercially available dyes and pigments, ease of preparation, and material stability. There are a variety of possible applications of nanoparticles of organic chromophores that derive from the photonic properties of both the component molecule and the nanoscaled dimensions of the particle. Many of these nanoparticles, when the porphyrin contains a redox-active transition metal (e.g. Fe, Co, Mn), are more efficient catalysts on a per porphyrin basis than the individual porphyrins in solution or individual porphyrins adsorbed onto supports. An understanding of nanoparticles surface interactions can be exploited to dictate the size of the deposited nanoparticles.