QBFEVAL'20 is the 2020 competitive evaluation of QBF solvers, and the fifteenth event aimed to assess the performance of QBF solvers. QBFEVAL'20 awards solvers that stand out as being particularly effective on specific categories of QBF instances. We warmly encourage developers of QBF solvers to submit their work, even at early stages of development, as long as it fulfills some very simple requirements. We also welcome the submission of QBF formulas to be used for the evaluation. Researchers thinking about using QBF-based techniques in their area (e.g., formal verification, planning, knowledge representation & reasoning) are invited to contribute to the evaluation by submitting QBF instances of their research problems (see the requirements for instances). The results of the evaluation will be a good indicator of the current feasibility of QBF-based approaches and a stimulus for people working on QBF solvers to further enhance their tools.