A bulk seed handling system (20) is provided to facilitate seed transfer from a distributor to a farm and then to a planter or the like. The handling system (20) includes one or more upright bin assemblies (22) adapted to be moved in a filled condition, and a trailer (24) designed to move the bin assembly (22) and unload seed therefrom. The bin assembly (22) includes a seed bin (26) having a lower unload opening (34) and supported by a frame assembly (38) including telescopic legs (50) shiftable between a retractable travel position and an extended bin support position. The trailer (24) includes a lift frame (60) operable to engage and elevate the bin assembly (22) for travel with the legs (50) thereof in a retracted position, and a seed-conveying arrangement including an intermediate conveyor (62) and a delivery conveyor (64). At an unloading site, the intermediate conveyor (62) is shifted to an unloading position in communication with the bin unload opening (34) and the delivery conveyor (64) in order to transfer seed from the bin.