Abstract: A quick-attach coupler for attaching an implement such as a bucket (15) to a machine such as a front end loader or backhoe. The coupler includes attachment structure (25, 29) for attaching the coupler to the machine, upper receiving structure (20) for receiving an upper coupling structure (18) on the implement and lower receiving structure (19) for receiving a lower coupling structure (17) on the implement. The lower receiving structure has an opening including a locating formation in the form of a threshold (19a) which retains the lower coupling structure (17) in the lower receiving structure, and latch structure (34) associated with the upper receiving structure (20) retain the upper coupling structure (18) within the upper receiving structure (20) and prevent the lower coupling structure (17) disengaging the locating formation (19a) of the lower receiving structure thus maintaining the attachment of the implement on the coupler.