Abstract: An inside corner form for forming an inside corner of a wall structure for casting concrete includes a central member for forming the corner, side members for forming portions of the walls adjacent the corner, an actuator for expanding and contracting the inside corner form and a lid for five sided pours. Slide lugs are provided to engage the central and side members such that the members are maintained in their proper orientations, while still permitting the members to slide relative to one another during the expansion and contraction of the form. A flowable material is injected between the central and side members for lubrication and to form a barrier to prevent grout from seeping between the members of the inside corner form and lid.