Developmental biologists have been fascinated with the long-standing mystery of how multicellular organisms, such as plants and animals, sense and control their organ size. In plants, leaves are a suitable experimental system for elucidation of the mystery, because they, like animal organs, inherently exhibit a determinate growth pattern, meaning that they possess genetic information for the control of their final size. The cell proliferation and expansion processes are prerequisites for growth, so that the genetic controls should converge on the 2 cellular processes and decide their rate or duration during leaf growth. Plant scientists have found dozens of genes involved in the control of the cellular processes, including the Arabidopsis thaliana GRF-INTERACTING FACTOR(GIF) family. The GIFfamily consists of 3 members, GIF1to GIF3, and encodes a class of transcription co-activators. Although the GIFfamily genes have been shown to play an essential role in the control of cell proliferation of the leaf organ, understanding of the spatio-temporal behaviors of GIFexpression, in both aspects of their promoters and proteins, has been limited to GIF1(also known as ANGUSTIFOLIA3, AN3). Here, we define kinematic growth properties of wild-type and gifleaf organs and present spatio-temporal expression patterns of all GIFgenes, thus providing comprehensive insights into biological roles and expression behaviors of the whole GIFfamily members during leaf growth.