Ethylene is a gaseous hormone which plays an essential role in a myriad of plant developmental processes. It promotes root hair formation, flowering in a number of species, fruit ripening and abscission and leaf and petal abscission. Ethylene can stimulate growth in hypocotyls of light-grown plants, and shoot growth in shaded conditions. On the other hand, it inhibits root growth, and hypocotyl elongation in the dark. In recent years, compelling molecular evidence has been gathered to support intricate connections between ethylene and other hormonal pathways that yield its well-known effects on plant growth. In this chapter, we will discuss the role of ethylene in both growth-stimulating and growth-inhibiting processes.