Bouëssel du Bourg et al. used molecular dynamics simulations combined with classical force fields to show that, for a similar chemistry (zinc-based zeolitic imidazolate frameworks, or ZIFs), the thermal expansion could vary both in sign and magnitude with the topology of the materials. We could also show that some ZIFs exhibit very large negative thermal expansion (NTE), i.e., they contract upon heating. That phenomenon is counter-intuitive in dense materials, but actually quite common in framework materials such as some oxides, zeolites, MOFs, etc. The identification of materials with tunable thermal expansion is an important axis of research, in particular in the design of novel nanostructure composites.