Alzheimer's disease (AD) is the most well-known neurodegenerative disorder, causing dementia. In recent decades, several studies have reported calcium dysregulation in AD occurring through the intervention of several calcium receptors and channels, and affecting different cellular compartments, such as mitochondria, the endoplasmic reticulum, lysosomes, and microdomains within the plasma membrane. Calcium signalling dysregulation is now considered a common proximal cause of dysfunctional neurons and glial supporting cells. This book gathers the newest results and advances in calcium signaling deregulation mechanisms in AD, how they are linked to other players involved in AD, and the potential therapies targeting calcium alterations to treat AD.