In 2004 the Paul Scherrer Institute was privileged to continue a series of two very successful
workshops, previously hosted by the SPring-8 Accelerator Division in 2001 [1
] and 2002 [2
] was held at the Hotel Kirchbühl in Grindelwald, Switzerland during December 6-10, where 47 accelerator physicists from 12 countries gathered to talk about orbit stability matters. Excellent orbit stability is one of the key issues in 3rd generation light sources since the orbit has to be stabilized typically to 1/10th of the beam size at the location of the insertion devices, translating to sub-micron stability requirements over time periods ranging from ms to days. The upcoming linear accelerator based 4th generation light sources also have tight tolerances on their residual trajectory jitter which induces the need for slow, fast and ``very fast'' multi-bunch feedforward/feedback systems. The aim of this workshop series is to give people involved in orbit stability issues an opportunity to share their experiences, identify problems and discuss solutions.