The time dependencies of capacitance and dissipation factor, for aluminum specimens supporting air‐formed or anodic films, have been measured at 103 Hz during immersion in near‐neutral chromate, dichromate, chloride, bromide, iodide, fluoride, and sulfate solutions. Supporting observations have been made using optical microscopy and scanning and conventional electron microscopy. Behavior in chromate and dichromate solutions is interpreted in terms of the healing of “mechanical” flaws originally present in air‐formed films and the thinning of anodic films down to a passive film thickness of about 25Aå. Results in bromide, iodide, and especially chloride solutions are interpreted in terms of pitting by dissolution of transiently exposed metal at the bases of flaws and subsequent undermining of the surface oxide film, which plays a relatively inert role throughout the process. A quantitative model, describing the effects of pit development from flaws on measured specimen impedances, is presented. Relatively little attack occurs in sulfate solution, whereas in fluoride solution the impedance changes are consistent with rapid removal of the surface oxide film and its replacement by a complex oxyfluoride. The general degree of aggression of the anions toward oxide‐coated aluminum increases in the order of dichromate, chromate, sulfate, iodide, bromide, chloride, fluoride.