Cellulose is a beta-1,4 linked glucose polymer that is synthesized by higher plants, algae and even by some bacteria and animals, making it the most abundant polymer on earth. As the major load bearing structure of the plant cell wall, it is hugely important in terms of plant growth and development, and in recent years it has gained interest for its biotechnological applications. Naturally, there has been a large concerted research effort to uncover the regulatory mechanisms underpinning cellulose synthesis. During the last century, several major breakthroughs in our understanding of cellulose synthesis in algae, bacteria, and plants have been pivotal in advancing the field of cellulose research, improving the likelihood that cellulose synthesis could be feasibly adapted for sustainable purposes. In this review, we will summarize the major hypotheses and advancements made during the last century on the regulation of cellulose biosynthesis, focussing on Arabidopsis thaliana.