Hydrogen (H) bonds can be used either for crystal engineering or for designing compounds capable of forming very stable glassy phases. Herein, a second type of directional non-covalent interaction, π-π stacking, is introduced to establish the interplay between both types of interactions on crystal and glass formation. For this purpose, two mexylaminotriazine derivatives incorporating 2,3,4,5,6-pentafluorostilbene groups (with or without a H-bond donor at the 2 position of the triazine) and their non-fluorinated analogues were synthesized to compare their glass-forming and crystallization properties. While all four compounds showed glass-forming ability, only the fluorinated compounds showed crystallization with kinetics strongly affected by the presence or absence of the H-bond donor group. X-ray diffraction of the pentafluorostilbene-containing derivatives revealed an extended π-π stacking interaction, different from that of 2,3,4,5,6pentafluorostilbene. These results, combined with infrared spectroscopy measurements, suggest that π-π stacking promotes crystallization, while hydrogen bonding impedes it, due to the higher conformational constraints imposed by π-π stacking, thereby decreasing the degrees of liberty and the possibilities for secondary interactions with other molecules.