 Abstract growth constitutes a powerful method to post-modulate material structures and functions without compromising their mechanical performance for sustainable use. However, the process is irreversible. To address this issue, we present a growing-to-growing strategy that enables thermosetting materials to either absorb or release components for continuously changing their sizes, shapes, compositions, and a set of properties simultaneously. This strategy is based on the monomapolymer equilibrium of networks in which supplying or removing small polymerizable components drives the networks towards expansion or contraction. We demonstrate that the size and mechanical properties of the resulting silicone materials can be significantly or finely tuned in both directions of growth and decomposition. Additionally, material structures can be selectively varied either uniformly or heterogeneous by the availability of fillers. Our strategy endows the materials with many appealing capabilities such as environment adaptivity, self-healing, and switchability of surface morphologies, shapes, and optical properties. Since monomapolymer equilibration exists in many polymers, we envision the expansion of the presented strategy to various systems for many applications. This article was authored by Xiaoshuanzhu, Yichu and Shen, Hao Hewei, John, and others.