A scroll compressor and a method for assembling a scroll compressor are provided. The scroll compressor may include a casing including a rotational shaft, a main frame coupled to an inside of the casing, a first scroll that revolves due to rotation of the rotational shaft, the first scroll being supported by the main frame, and a second scroll disposed on or at a side of the first scroll to define a plurality of compression chambers together with the first scroll. The second scroll may include a head plate including a wrap, and at least one coupling guide that extends from the head plate. The at least one coupling guide may include a first reference pin coupling hole, into which a reference pin may be inserted, and a guide hole, into which a coupling member may be inserted.