A pharmaceutical formulation comprising molindone as the active pharmaceutical ingredient and having: (a) a modified-release composition comprising: (i) molindone, (ii) at least one release controlling polymer, wherein the release controlling polymer consists of one or more non-pH-dependent polymers selected from the group consisting of hydroxypropyl cellulose, hypromellose (hydroxypropyl methyl cellulose), methyl cellulose, polyethylene oxide, acacia, carbomer homopolymer type A NF; carbomer homopolymer type B NF, hydroxyethyl cellulose, carrageenan, tragacanth, xanthan gum, povidone, alginic acid and salts thereof, polyvinyl alcohol, carboxymethylcellulose; ethylcellulose, cellulose acetate, cellulose acetate butyrate, poly(ethyl acrylate-co-methyl methacrylate) ethyl acrylate methyl methacrylate copolymer, poly (ethyl acrylate-co-methyl methacrylate-cotrimethylammonioethyl methacrylate chloride), polyvinyl acetate, and cellulose acetate propionate, and (iii) at least one stabilizer selected from the group consisting of acidifying agents and hydrophobizing agents; wherein the total amount of water content in the formulation is not more than 5 % by weight of the formulation; and, optionally, (b) an additional formulation comprising molindone in an immediate release, extended release, or delayed release formulation. (a) a modified-release composition comprising: (i) molindone, (ii) at least one release controlling polymer, wherein the release controlling polymer consists of one or more non-pH-dependent polymers selected from the group consisting of hydroxypropyl cellulose, hypromellose (hydroxypropyl methyl cellulose), methyl cellulose, polyethylene oxide, acacia, carbomer homopolymer type A NF; carbomer homopolymer type B NF, hydroxyethyl cellulose, carrageenan, tragacanth, xanthan gum, povidone, alginic acid and salts thereof, polyvinyl alcohol, carboxymethylcellulose; ethylcellulose, cellulose acetate, cellulose acetate butyrate, poly(ethyl acrylate-co-methyl methacrylate) ethyl acrylate methyl methacrylate copolymer, poly (ethyl acrylate-co-methyl methacrylate-cotrimethylammonioethyl methacrylate chloride), polyvinyl acetate, and cellulose acetate propionate, and (iii) at least one stabilizer selected from the group consisting of acidifying agents and hydrophobizing agents; wherein the total amount of water content in the formulation is not more than 5 % by weight of the formulation; and, optionally, (i) molindone, (ii) at least one release controlling polymer, wherein the release controlling polymer consists of one or more non-pH-dependent polymers selected from the group consisting of hydroxypropyl cellulose, hypromellose (hydroxypropyl methyl cellulose), methyl cellulose, polyethylene oxide, acacia, carbomer homopolymer type A NF; carbomer homopolymer type B NF, hydroxyethyl cellulose, carrageenan, tragacanth, xanthan gum, povidone, alginic acid and salts thereof, polyvinyl alcohol, carboxymethylcellulose; ethylcellulose, cellulose acetate, cellulose acetate butyrate, poly(ethyl acrylate-co-methyl methacrylate) ethyl acrylate methyl methacrylate copolymer, poly (ethyl acrylate-co-methyl methacrylate-cotrimethylammonioethyl methacrylate chloride), polyvinyl acetate, and cellulose acetate propionate, and (iii) at least one stabilizer selected from the group consisting of acidifying agents and hydrophobizing agents; wherein the total amount of water content in the formulation is not more than 5 % by weight of the formulation; and, optionally, (b) an additional formulation comprising molindone in an immediate release, extended release, or delayed release formulation.