Abstract: Compositions for the controlled delivery of active ingredients, for example, drugs, cosmetic materials, and agricultural materials. The compositions include a multiplicity of particles, each of the particles comprising (1) a microstructure comprising a semicrystalline polymer which has a peak melting temperature, Tp, of at least 20° C., and (2) the active ingredient. The microstructure comprises (i) crystalline domains of the semicrystalline polymer, the crystalline domains being separate from each other, and (ii) amorphous domains of the semicrystalline polymer, the amorphous domains providing a multiplicity of tortuous paths between the crystalline domains. At least part of the active ingredient is present in the amorphous domains. One of many valuable uses for the compositions is to provide a coating on a seed, for example a coating containing one or more of an insecticide, a fungicide, a nutrient, a biotic, a growth regulator and an herbicide.