This thoroughly peer-reviewed proceedings of the ninth international workshop on low temperature detectors provides a snapshot of the state-of-the-art in low temperature particle and radiation detectors. In 134 original research papers, the physics and applications of this new and extremely high performance type of detectors is described in detail. This includes their application to such diverse fields as astrophysics at all wavelengths from the submillimeter to gamma-ray, dark matter searches, neutrino astrophysics, atomic physics, nuclear physics, biophysics, and materials science.