Abstract: Prosthetic feet that provide for variable and adjustable stiffness are provided. A foot element can include a tongue portion defined or formed by a slot in the foot element that at least partially separates the tongue portion from a remainder of the foot element. The tongue portion can be operably connected to the remainder of the foot member to increase the stiffness of the foot member or operably disconnected from the remainder of the foot member to increase the flexibility of the foot member. The prosthetic foot further includes a mechanism for adjusting whether the tongue portion is operably connected or disconnected from the remainder of the foot member. The mechanism can be selectively actuated to adjust the stiffness of the foot element in dorsiflexion and/or plantarflexion and/or to adjust the degree to which the tongue portion is allowed to flex relative to the remainder of the foot member.