Most cis-regulatory elements are located near one or more binding sites for transcription factors, some of which are activators of transcription and others repressors of transcription. The rate of transcription of any gene in any type of cell is therefore determined by the combination of transcription factors that are present in the cell and by the relative balance of activators and repressors. Regulation of gene transcription according to the mix of transcription factors in the cell is known as combinatorial control. Combinatorial control of transcription is another general principle often seen in all multicellular organisms at many stages of development. Here, we discuss flower development as an example of this general principle.