The asymmetric unit of the title salt, C10H11N2 (+)·C4H5O4 (-), consists of two independent 5-amino-6-methyl-quinolin-1-ium cations and two 3-carb-oxy-propano-ate anions. Both cations are protonated at the pyridine N atoms and are essentially planar, with maximum deviations of 0.026 (3) and 0.016 (2) Å. In the crystal, the cations and anions are linked via N-H⋯O and O-H⋯O hydrogen bonds, forming a layer parallel to the ab plane. In the layer, weak C-H⋯O hydrogen bonds and π-π stacking inter-actions, with centroid-to-centroid distances of 3.7283 (15) and 3.8467 (15) Å, are observed. The crystal structure also features weak C-H⋯O hydrogen bonds between the layers.