An adjustable riser cage retains varying length adapters. For example, the adjustable riser cage may support a short adapter card, a ¾ length adapter card, or a long adapter card. The adjustable riser cage includes a riser portion and an extension portion. The riser portion includes one or more guidance features and a plurality of first retention members. The extension portion is slide ably supported against only the one or more guidance members, and includes a second retention member configured to engage with a particular first retention member depending upon a length of the adapter card to be supported. The adjustable riser cage may be installed into a larger electronic system having a plurality of electronic components. The adjustable riser cage allows for increased access to the electronic components because the extension portion is not supported by external or non-integral support features that may block access to the electronic components.