This book constitutes the refereed proceedings of the 22nd International Symposium on Practical Aspects of Declarative Languages, PADL 2020, held in New Orleans, USA, in January 2020. The 10 full and 4 short papers were carefully reviewed and selected from 24 submissions. The papers present original work emphasizing novel applications and implementation techniques for all forms of declarative concepts, including programming with sets, functions, logic, and constraints. The papers are organized in the following topical headings: logical engines and applications; answer set programming systems; memory and real-time in functional programming; reasoning and efficient implementation; and small languages and implementation.