This book constitutes the proceedings of the 13th IFIP WG 8.5 International Conference on Electronic Participation, ePart 2021, held in Granada, Spain, in September 2021, in conjunction with IFIP WG 8.5 Electronic Government (EGOV 2021), the Conference for E-Democracy and Open Government Conference (CeDEM 2021). The 16 full papers presented were carefully reviewed and selected from 37 submissions. The papers are clustered under the following topical sections: digital participation, digital society, digital government and legal issues.