Locomotion - the act of moving from one location to another - involves many cerebral cortical areas. It is unclear how these different cortical regions interact during locomotion to produce a coordinated behavioral output, how these interactions differ from those at rest, or how these regions are recruited into the locomotive functional state. Optically clear, morphologically conformant polymer windows are implanted in the skulls ofThy1-GCaMP6f mice expressing the Ca2+ indicator GCaMP6f in Layer II/III and Layer V pyramidal neurons. These prosthetic windows allow for wide field-of-view optical imaging of the majority of the dorsal cerebral cortex at 1x magnification. The mice are head fixed on a freely moving disk that allows free limb and body movements including walking. Wide field-of-view Ca2+ imaging is performed during rest, spontaneous locomotion, and cued locomotion (20 Hz acquisition at a spatial resolution of 25 x 25 µm). Rotation of the freely moving disk is recorded with a rotary encoder. The wide-field imaging data is divided into independent functional regions using spatial independent component analysis (ICA). Time series are extracted from the ICs and correlated to compute functional interactions, which reveal dynamic functional networks in the mouse cortex in relation to locomotion. Preliminary analyses show that just before the animal begins walking, there is an overall increase in correlation across cortical region. This increase subsides as locomotion proceeds. The functional cortical network then changes in shape, with individual functional regions becoming associated with different sub-networks during locomotion than at rest. Understanding these cortical interactions in rest and locomotion will help elucidate how the cerebral cortex generates the locomotor state.