This workshop series focuses on developments towards longitudinal diagnostics for electron bunches in current and future accelerators. We want to focus in particular on collaborations on this topic, and we especially welcome joint contributions from several labs. The workshop will consist of two parts: on Wednesday, working groups will convene, with the goal of exchanging ideas, and planning collaborations and joint measurements. We are presently planning the following working groups: 1) Compression Monitor — Christo & Franziska 2) Electro-Optical Diagnostics — Bernd & Steve 3) sub-fs Diagnostics — Minjie & Rasmus 4) KALYPSO (fast digitizer) — Michele & Dariusz If you would like to suggest another working group, please contact one of the organizers! The second part of the workshop will be a joint session of all working groups, starting on Thursday morning. As in previous years, contributions will be accepted in the form of a poster (format: portrait A0). You will get a chance to promote your poster in a 300-second presentation. Please give your slides to your working group leader on Wednesday.