The invention generally relates to a selectable boot articulation and support system. One embodiment of the present invention relates to a boot system including an intercoupled upper and lower shell configured to encase a user's foot and lower leg. The boot system further includes an articulation system effecting the articulation between the upper and lower shell. The articulation system includes an instep member coupled and positioned with respect to the upper shell in a manner that facilitates selection between a locked configuration and an unlocked configuration. The unlocked configuration provides increased articulation and decreased stiffness between the upper and lower shell with respect to the locked configuration. The instep member may include a releasable dorsal coupling between portions of the upper shell. The instep member may also include one or more moveable lateral couplings with the upper shell.