In recent years, Acinetobacter baumannii has emerged as a major threat to human health. Yet studies to uncover the molecular mechanisms used by A. baumannii to mediate human infections have only recently begun. For example, the methods used by A. baumannii to resist antibacterial treatment are not fully understood. Using a candidate approach, we sought to identify proteins found in the A. baumannii cell envelope that are important for resistance to antimicrobial compounds. We screened selected mutants in genes needed for assembly of the bacterial cell envelope, biofilm formation, or capsule production for sensitivity to different antibiotics and detergents. Compared to wild-type, these mutants displayed an increased sensitivity to bacitracin yet not to vancomycin, both antibiotics that target the cell wall. Only the ompA and lnt mutants had significantly increased sensitivity to the DNA gyrase inhibitor novobiocin. Similarly, there was also a spectrum of sensitivity to bile salts, with ompA and lnt mutants being most sensitive while pgaA, pgaB, and capA mutants showed a modest growth defect. While we do not fully understand the specificity of these sensitivity profiles, our findings suggest a potential use for these antimicrobial compounds in genetic selections for mutants that disrupt cell envelope biogenesis. This approach could potentially inform future efforts to combat multi-drug resistant Acinetobacter infections.