Abstract: A collapsible shelter. One embodiment may include a lower shelter portion that has substantially rigid lower walls and a floor therein. An upper shelter portion that has substantially rigid upper walls and a roof is telescopingly coupled to the lower shelter portion such that the upper shelter portion is selectively vertically moveable relative to the lower shelter portion between a first collapsed position and a second extended position. In addition, the shelter may include a selectively releasable retainer assembly for selectively supporting the upper shelter portion relative to the lower shelter portion in the second extended position.