Super simple to put together and very sturdy. This shelving unit was simple to put together without any help from a second person, and with no heavy pieces. The complete unit is plenty heavy and sturdy once assembled, but none of the individual pieces are heavy or cumbersome and everything slides together simply and with no tools. Once assembled, shelves are reasonably easy to move if they are needed at different heights. And, the shelving unit is plenty strong with no warping of the shelves.