The present invention concerns a method for increasing plant yield relative to corresponding wild type plants. More specifically, the present invention concerns a method for increasing plant yield comprising introducing into a plant a nucleic acid encoding a cyclin D3 (CYCD3) polypeptide under the control of a promoter capable of preferentially expressing the nucleic acid in the endosperm of seeds. The present invention also concerns plants comprising an isolated nucleic acid encoding a CYCD3 polypeptide under the control of a promoter capable of preferentially expressing the nucleic acid in the endosperm of seeds, which plants have increased yield relative to corresponding wild type plants. The invention also provides constructs useful in the methods of the invention.