The gold(I)‐catalyzed reaction of 1,3‐enynes with alkenes gives rise to 1‐vinylcyclobutenes by a formal [2+2] cycloaddition. The corresponding reaction of alkynes or 1,3‐enynes with 1,3‐dienes or other dienes also gives cyclobutenes. Cyclobutenes can be transformed to a variety of products by one‐pot reactions involving cycloaddition, ring opening, expansion, or contraction.