It took about 45 minutes to assemble. The pieces fit together great and holes aligned. The back screws in step 11 were very tough to put in. The stairs are not completely straight and the screw was tough to get in. I have three children and put thing together often, I would say this was very easy over all to assemble. I also really like the quality of the materials. My daughter will get several years of play out if it. Great product now let's see how it holds up!