The Drosophila gene jim lovell (lov) encodes a putative transcription factor of the BTB/POZ (Bric-a-Brac, Tramtrack, Broad/Pox virus and Zinc finger) domain class that is expressed in many elements of the developing larval nervous system. Lov has roles in innate behaviors such as larval locomotion and adult courtship. I have identified new roles of lov in controlling endopolyploid growth. Endopolyploid growth occurs when cells repeatedly duplicate the genomic DNA without cell division. This type of growth is a normal feature of growth in some plants and animal tissues and is also used by cancer cells for survival. Most of the rapid growth of the Drosophila larva is achieved by this mechanism. I discovered that decreasing lov expression in endopolyploid larval tissues such as the tracheae and the salivary gland, reduces their cell size and endoploidy levels. dMyc is a well-known regulator of both mitotic and endopolyploid growth in Drosophila, acting mainly on nucleolar functions. I have shown that Lov is a nucleolar protein and that decreasing Lov levels can partially suppress the effects of dMyc on endopolyploid growth. I have also established that Lov interacts with another BTB/POZ domain protein called Ribbon (Rib) in controlling endopolyploid growth. Lov also regulates tracheal growth by affecting transcription of the uninflatable (uif) gene, which encodes an apical plasma membrane protein. Together, my findings indicate that Lov’s role in endopolyploid growth involves interactions with dMyc, Rib, and Uif.