Polyalkylene glycol compositions having reduced low molecular weight oligomers are disclosed. Some compositions, particularly polyethylene glycol compositions, have a number average molecular weight range from about 3000 to about 10,000 g/mol and have a total oligomer concentration of less than about 400 ppm of all oligomers having a molecular weight of less than or equal to 812 g/mol and a total oligomer concentration of less than about 50 ppm of all oligomers having a molecular weight of less than or equal to 240 g/mol. Other polyalkylene compositions, particularly polyethylene glycol compositions, are characterized by a total oligomer concentration of less than about 90 ppm of all oligomers having a molecular weight less than or equal to 460 g/mol and are obtained without further processing to remove oligomers having a molecular weight of less than about 460 g/mol. Methods for making such compositions are also disclosed.