We have used infrared spectroscopy in both the ground and excited electronic states to determine the structural geometries of hydrogen-bonded clusters involving aminophthalimide molecules. This provides a higher level of structural information than available through an inertial measurement such as rotational coherence spectroscopy. Clusters of interest include the two conformers each of the water n=1 cluster with 4-aminophthalimide (4AP) and 4-amino-N-methylphthalimide (4ANMP), which are shown to be attached by proton donation to different >C O groups. The corresponding n=1 water cluster of 3-aminophthalimide (3AP) is present as only a single conformer, consistently with the presence of an intramolecular hydrogen bond. Both 3AP/(H 2 O) 1 and 4AP/(H 2 O) 1 are found to form bridging structures between the imide N-H bond and an adjacent >C O group. On the other hand, the water dimer clusters of 4AP and 4ANMP bridge the NH 2 and the adjacent >C O group.Pure dimers of the aminophthalimides have simple infrared spectra in the electronic ground states, which indicate symmetrical structures. The 4AP and 4ANMP dimers form a double hydrogen-bonded bridge across the 2,4 positions and their complex infrared spectra in the excited state show evidence of strong interactions, which may involve excited-state intermolecular double proton transfer. On the other hand, the 3AP dimer is doubly hydrogen bonded across the 1,7 positions, and appears to show evidence of excited-state single intramolecular proton transfer. Possible reasons for these differences are discussed.