We perform ab initio calculations needed to predict the cross-section of an experimentally accessible (1 + 1 ′ ) resonance-enhanced multiphoton dissociation (REMPD) pathway in AlH + . Experimenting on AlH + ions held in a radiofrequency Paul trap, we confirm dissociation via this channel with analysis performed using time-of-flight mass spectrometry. We demonstrate the use of REMPD for rotational state analysis, and we measure the rotational distribution of trapped AlH + to be consistent with the expected thermal distribution. AlH + is a particularly interesting species for ion trap work because of its electronic level structure, which makes it amenable to proposals for rotational optical pumping, direct Doppler cooling, and single-molecule fluorescence detection. Potential applications of trapped AlH + include searches for time-varying constants, quantum information processing, and ultracold chemistry studies.