The present invention provides a support assembly for a lighting fixture that allows for the adjustment and positioning of a lamp about both a horizontal and a vertical axis using only one locking mechanism. The support assembly includes a first support member that is pivotably attached to a second support member. The support assembly also includes a cylindrical sleeve to which the second support member is adjustably engaged. Both support members include at least one leg extending therefrom. The locking mechanism includes a pivoting brake shoe that can engage the cylindrical sleeve so as to secure the lamp into position about a vertical axis. The locking mechanism also includes a thumbscrew that is housed within a slot defined within a leg of the first support member, and that engages both the brake shoe and a leg on the second support member.