Breakaway riding boot

A riding boot comprising a sole, a heel, and an upper defining a foot-receiving portion and a lower leg-receiving portion, wherein the lower leg-receiving portion of the upper has a lengthwise opening extending down the back of the boot from the top of the boot to the heel of the boot, and fastening means for releasably holding opposing edges of the upper defining the opening together during normal usage of the boot, and for breaking open in response to forces created in the boot if the wearer of the boot falls from a horse and the wearer's foot is caught in a stirrup so as to provide quick release of the wearer's foot from the boot, wherein the boot includes a heel insert having an upper edge which diverges downwardly toward its center and defines a central tip located substantially at the base of the lengthwise opening above an insole of the boot so as to allow a degree of up-and-down movement of the user's heel during normal walking while providing quick release of the fastening means in the event the user's heel rises above the tip and exerts outward pressure on the fastening means.