The Swiss Election Study (Selects) 2023 consists of four complementary components: The Post-Election Survey (PES), the Panel Survey, the Candidate Survey, and the Media Analysis. The study design is largely inspired by Selects 2019. The PES and Candidate Survey are mixed-mode surveys (online/paper), with a push-to-web design, whereas the Panel Study is an online survey. In April 2022, a call for questions/modules was opened to allow researchers from Switzerland and abroad to include novel questions into one or different components of Selects. Ten out of 14 submitted proposals were selected by the Selects Commission after a review process conducted by internationally renowned election researchers, and were fully or partially integrated into one or several components of Selects 2023. The Selects surveys were approved by the Ethics commission of the University of Lausanne. Post-Election Survey (PES): The Post-Election Survey consists of 5033 respondents who answered the questionnaire in the period from 23 October 2023 to 12 January 2024. The survey was conducted in a sequential mixed mode with web offered as the first option: 90% responded in this way, while 10% responded by returning the paper questionnaire that was sent out with the second reminder to those that had not completed the web questionnaire. The sampling was based on a representative sample of around 2’600 Swiss citizens, with an oversampling of small cantons to have at least 50 respondents in every canton. An additional oversampling was done in the cantons of Geneva and Ticino thanks to additional funding from these cantons. The sample was drawn by the Federal Statistics Office from the SRPH. Sample members received an unconditional incentive (10 CHF in cash) that was sent out with the invitation letter. Module 6 Questionnaire of the Comparative Study of Electoral Systems was included into the PES. Panel Survey: The Panel Survey studies the evolution of opinion and vote intention/choice during the different phases of the election cycle. In 2023, three waves were conducted: the first before the main campaign period (June/early August), the second during the election campaign (September/October), and the third after the elections (October/November). The initial random sample (stratified by big region/NUTS II) was taken by the Federal Statistics Office from the SRPH. 8197 individuals responded to the first wave, 6077 to the second wave, and 5579 to the third wave. Conditional incentives were used in all three panel waves (lottery of 5x300 CHF in wave 1, 10 CHF in cash in waves 2 and 3). This three-wave panel will be continued with annual follow-up waves until the 2027 elections. Candidate Survey: The Candidate Survey was carried out among all candidates for the National Council and the Council of States in the framework of the international Comparative Candidate Survey (CCS) project, based on the Round III questionnaire. The survey collects data on the biography, campaign activities, and policy position of the candidates. Among others, the information gathered makes possible the study of underlying factors of candidates’ electoral success, as well as of issues of representation and linkage between voters and elites. In 2023, 2527 out of 5997 candidates participated in the Candidate Survey. This survey was conducted by FORS in collaboration with Politools and the University of Bern. Media Analysis: On behalf of Selects, the Center for Research & Methods at the University of Applied Sciences in Business Administration Zurich (HWZ) conducted a Media Analysis. The Media Analysis is a supplement to the Panel Survey and makes it possible to analyse the election campaign in the media and its influence on voters' opinion formation. A media study has been part of Selects since 2003. In 2023, 116 daily or weekly newspapers (print and online) were content-analyzed in the period between 1 May 2023 and 31 October 2023.