The article discusses various reports published within the issue, including one by Natalia Pivovarova and Brian Andrews on the perimitochondrial environment regarding Ca2 homeostasis, one by Christos Chinopoulos and Vera Adam-Vizi on processes mediating Ca2 uptake through inner mitochondrial membrane, and one by Anatoly Starkov, on identifying the molecular entities that facilitate matrix Ca2 precipitation and those that mediate Ca2 uptake.