A marker has a cap with a reverse clip, which opens toward the closed end of the cap, that is, in the same direction as the force applied to remove the cap, thereby allowing the cap to be removed with one hand without dislodging the reverse clip from its attachment. To facilitate single-handed removal and replacement of the marker, the cap has a semi-tubular cap extension, terminating in a flange from which the reverse clip extends. The cap extension acts as a guide for replacing the marker in the cap with one hand, while the flange provides a flat surface against which downward thumb pressure can be applied to separate the cap from the marker as the latter is pulled up with the other fingers of the same hand.