The present invention addresses the need for a collapsible filter that is easily assembled and installed. The collapsible filter comprises top and bottom arms rotatably attached to the top and bottom edges of two end caps. A pleated filter media is provided attached to at least one of the end caps. The present invention also addresses the need for mechanisms to facilitation the expansion of the pleated filter media, utilizing spring-like devices or other materials that may be compressed but expand to a natural state. Similarly, the present invention further addresses the need for mechanisms that allow for controlling the distance between adjacent pleats within a pleated, collapsible filter media. The present invention recognizes that a combination of these approaches may be utilized to provide a collapsible filter that is easily constructed at a manufacturing facility, assembled in the field, and installed within a system having need for a filter.