The control of basal body (BB) and ciliary number is important to ensure normal cilia-dependent fluid flow in multi-ciliated cells. In the ciliate, Tetrahymena thermophila BBs are organized into rows at the cell cortex and nucleate cilia for cellular motility. Importantly, the number of BBs remains relatively constant in Tetrahymena cells (Nanney, 1971). How this homeostatic balance of BB frequency is controlled during each cell cycle remains poorly understood. The mutant, big1-1, that causes larger cells with more BBs was used to investigate how cells regulate BB number (Frankel, 2008). Big1-1 mutant cells are longer and wider than wild type (WT) cells and possess supernumerary BBs. This suggests that BB assembly promiscuously increases in big1-1 cells. To investigate how big1-1 cells gain more BBs, we measured the rates of new BB duplication. Consistent with the increased number of BBs in big1-1 cells, new BB duplication and assembly is elevated. Moreover, big1-1 BBs mature more rapidly than wild type BBs. This suggests that rapid BB maturation renders new BBs competent to assemble more BBs, thereby increasing rate of new BB assembly at each cell cycle. Elevated temperature exacerbates the big1-1 BB amplification and corresponding cell size increase. Conversely, media starvation of big1-1 cells restores BB number and cell size to nearly normal levels. Also, we observe that big1-1cells contain similar BB density throughout their ciliary rows. Instead, we show that big1-1 accommodate their supernumerary BBs in extra ciliary rows that are formed through in a ciliary force-dependent mechanism. We find that the regulation of Tetrahymena BB number and cell size are coupled. The increase in cell size results from more BBs per ciliary row and an increase in the number of ciliary rows. Collectively, this suggests that big1-1 mutant cells lengthen and widen to accommodate their supernumerary BBs and to maintain normal BB density. The counting and regulation of BB number in Tetrahymena is necessary for daughter cells to properly inherit sufficient BBs for cell motility. In summary, Tetrahymena BB number is tightly regulated thereby ensuring normal cell size.