The airways are continuously challenged by a variety of stimuli including bacteria, viruses, allergens, and inflammatory factors that act as agonists for G protein-coupled receptors (GPCR). Intracellular calcium (Ca(2+) (i)) mobilization in airway epithelia in response to extracellular stimuli regulates key airway innate defense functions, e.g., Ca(2+)-activated Cl(-) secretion, ciliary beating, mucin secretion, and inflammatory responses. Because Ca(2+) (i) mobilization in response to luminal stimuli is larger in CF vs. normal human airway epithelia, alterations in Ca(2+) (i) signals have been associated with the pathogenesis of CF airway disease. Hence, assessment of Ca(2+) (i) signaling has become an important area of CF research. This chapter will focus on measurements of cytoplasmic and mitochondrial Ca(2+) signals resulting from GPCR activation in polarized primary cultures of normal and CF human bronchial epithelia (HBE).