These working notes contain the papers presented at SPARK 2019: the 12th International Scheduling and Planning Applications woRKshop held on 11th July in Berkeley, California, USA. We are once more very pleased to continue the tradition of representing more applied aspects of the planning and scheduling community and to present a pipeline that will enable increased representation of applied papers in the main ICAPS conference. For the first time, SPARK 2019 used an open review process.@en