Superconducting qubits are one of the most promising platforms for realizing the quantum circuit model of computation in a physical machine. Indeed, over the last 30 years rapid progress has been made in the design, fabrication, and control of superconducting qubit systems, culminating in a number of recent demonstrations of quantum error correction. However, much yet remains to be done if superconducting qubits are to eventually be used to perform useful tasks, and in this thesis we report on some progress in characterizing and mitigating sources of energy relaxation in superconducting qubits, which is one of the most critical sources of error in current hardware.