Significance Bacteriophages (“phages,” viruses that infect bacteria) are an important source of selection for bacterial populations. Phages use various structures to infect bacterial cells, and bacteria often evolve phage resistance by losing or modifying these structures. We examine a phage that uses two structures that also provide Escherichia coli cells with antibiotic resistance. We show that phage selection can result in bacteria evolving phage resistance by losing or modifying the structures. When phage resistance evolves, the bacteria sometimes also show increased antibiotic sensitivity. This result indicates an evolutionary trade-off between phage resistance and antibiotic resistance. However, we also discovered bacterial mutations that avoid the trade-off. We discuss the potential use of phage selection and evolutionary trade-offs in treating bacterial infections., Bacteria frequently encounter selection by both antibiotics and lytic bacteriophages. However, the evolutionary interactions between antibiotics and phages remain unclear, in particular, whether and when phages can drive evolutionary trade-offs with antibiotic resistance. Here, we describe Escherichia coli phage U136B, showing it relies on two host factors involved in different antibiotic resistance mechanisms: 1) the efflux pump protein TolC and 2) the structural barrier molecule lipopolysaccharide (LPS). Since TolC and LPS contribute to antibiotic resistance, phage U136B should select for their loss or modification, thereby driving a trade-off between phage resistance and either of the antibiotic resistance mechanisms. To test this hypothesis, we used fluctuation experiments and experimental evolution to obtain phage-resistant mutants. Using these mutants, we compared the accessibility of specific mutations (revealed in the fluctuation experiments) to their actual success during ecological competition and coevolution (revealed in the evolution experiments). Both tolC and LPS-related mutants arise readily during fluctuation assays, with tolC mutations becoming more common during the evolution experiments. In support of the trade-off hypothesis, phage resistance via tolC mutations occurs with a corresponding reduction in antibiotic resistance in many cases. However, contrary to the hypothesis, some phage resistance mutations pleiotropically confer increased antibiotic resistance. We discuss the molecular mechanisms underlying this surprising pleiotropic result, consideration for applied phage biology, and the importance of ecology in evolution of phage resistance. We envision that phages may be useful for the reversal of antibiotic resistance, but such applications will need to account for unexpected pleiotropy and evolutionary context.