A children's play yard comprising: a play yard frame comprising: one or more lower horizontal frame members ; one or more vertical frame members attached to said lower horizontal frame members , wherein at least a portion of said vertical frame members extends upwardly from said lower horizontal frame members ; and one or more movable retention members operatively connected to said vertical frame members and configured to move between an inward receiving orientation and a retaining orientation; wherein said moveable retention members include a lower end pivotally connected to one of said vertical frame members in order to permit said moveable retention members to pivot between said inward receiving orientation and said retaining orientation; and a removable play yard liner comprising: one or more sidewalls ; and one or more engagement features configured to engage said one or more moveable retention members ; wherein said sidewalls of said play yard liner extend between said moveable retention members of said play yard frame and define a bounded area within said play yard when said engagement features are engaged with said retention members and said retention members are positioned in said retaining orientation. a play yard frame comprising: one or more lower horizontal frame members ; one or more vertical frame members attached to said lower horizontal frame members , wherein at least a portion of said vertical frame members extends upwardly from said lower horizontal frame members ; and one or more movable retention members operatively connected to said vertical frame members and configured to move between an inward receiving orientation and a retaining orientation; wherein said moveable retention members include a lower end pivotally connected to one of said vertical frame members in order to permit said moveable retention members to pivot between said inward receiving orientation and said retaining orientation; and a removable play yard liner comprising: one or more sidewalls ; and one or more engagement features configured to engage said one or more moveable retention members ; one or more lower horizontal frame members ; one or more vertical frame members attached to said lower horizontal frame members , wherein at least a portion of said vertical frame members extends upwardly from said lower horizontal frame members ; and one or more movable retention members operatively connected to said vertical frame members and configured to move between an inward receiving orientation and a retaining orientation; wherein said moveable retention members include a lower end pivotally connected to one of said vertical frame members in order to permit said moveable retention members to pivot between said inward receiving orientation and said retaining orientation; and a removable play yard liner comprising: one or more sidewalls ; and one or more engagement features configured to engage said one or more moveable retention members ; wherein said sidewalls of said play yard liner extend between said moveable retention members of said play yard frame and define a bounded area within said play yard when said engagement features are engaged with said retention members and said retention members are positioned in said retaining orientation. <EOS>