The nucleation and growth of crystalline materials from solution is a process of pivotal importance for a variety of industrial applications ranging from materials synthesis to pharmaceutical manufacturing. The assembly process can be generally characterised in two stages, crystal nucleation and growth. The former plays a pivotal role in the definition of the bulk structure of materials, while the latter defines the shape of crystalline particles. Understanding and modelling these fundamental assembly steps at the molecular scale is key to develop rational approaches towards the design of innovative products and efficient manufacturing processes.