A process of making Form A of atazanavir sulfate comprises: a) mixing atazanavir free base with a solvent selected from the group consisting of methanol (MeOH), ethanol (EtOH), isopropanol (IPA), N-methylprrolidone (NMP) and combinations thereof; b) reacting sulfuric acid with the atazanavir free base in the mixture formed in step a) to form a reaction solution comprising atazanavir sulfate; c) mixing an antisolvent with the reaction solution; d) seeding the mixture formed in step c) with an effective amount of Form A of atazanavir sulfate to form a seeded mixture comprising Form A of atazanavir sulfate; and e) isolating Form A of atazanavir sulfate in solid form from the seeded mixture; wherein the antisolvent is selected from the group consisting of methyl tert-butyl ether (MTBE), ethyl acetate (EtOAc), acetonitrile (MeCN), isopropyl acetate (IPAc), cyclohexane, and combinations thereof. In one alternative, step c) may be performed before step b). In another alternative, step d) may be carried out concurrent with or prior to step c).