A trailer jack capable of rapid gross and incremental adjustments in height adapted for attachment to a trailer. The jack is comprised of an inner member nested within an outer member, a collar, a housing and a pin. The inner member is threadably connected to the outer member with a bolt having a crank attached at one end. The bolt enables incremental adjustments in the trailer height by extension and retraction of the inner member with respect to the outer member. The connected outer and inner members are secured to the trailer with a pin inserted through the housing, a hole in the collar and one of a plurality of longitudinal holes in the outer member. To create rapid gross adjustments in the trailer height, the pin is retracted, a different hole in the outer member is registered with the hole in the collar and the pin re-inserted.