ABSTRACT: Supramolecular self-assembly has attracted increasing attention as a breakthrough methodology in the fields of nanoscience and nanotechnology. Herein, a perylene dianhydride derivative (TP-PDA) self-assembles into well-defined nanospheres through a nucleation-growth process. The mechani**s of this process were explored by using spectral ****ysis, dynamic light scattering (DLS), and scanning electron microscopy (SEM). In situ DLS and in situ SEM both revealed that the size of the aggregated nanospheres increases with time until the formation of equilibrium H-aggregates. This shows that TP-PDA undergoes a kinetically trapped assembly with a rapid transformation into the thermodynamically favored form, and this process can be finely tuned by reducing the concentration and increasing the temperature. Weak intermolecular forces, such as p–p stacking, hydrogen bonding, and solvophobic interactions, play an important role in the formation of nanostructures. This work inspired us to explore other kinetically trapped supramolecular assemblies that might be easily ignored due to the short trapping time of commonly used experimental timescales.