Since the evolution of species from oceans to land, the adrenal steroid hormone, aldosterone, has played a critical role in the maintenance of fluid and sodium homeostasis. Aldosterone production is normally tightly controlled by circulating potassium (K+) and the renin-angiotensin system (RAS). The adrenal’s capacity to produce aldosterone relies heavily on the expression of a single enzyme, aldosterone synthase (CYP11B2). This enzyme carries out the final reactions in the synthesis of aldosterone and is expressed almost solely in the adrenal zona glomerulosa. Our research has demonstrated that angiotensin II and K+ cell signaling pathways converge on calcium-dependent pathways that increase CYP11B2 expression and aldosterone production. This process involves activation of calmodulin (CaM), CaM kinases, and select transcription factors, ending with increased CYP11B2 expression and aldosterone production. From a disease standpoint, aldosterone excess is the most common of all adrenal disorders. The prevalence of autonomous aldosterone excess (primary aldosteronism, PA) occurs in approximately 1 in 30 adults, accounting for up to 10% of hypertension and up to 20% of resistant hypertension cases. The major causes of PA are adrenal aldosterone-producing adenomas (APA) and adrenal idiopathic hyperaldosteronism (IHA). In both conditions, CYP11B2 expression and aldosterone synthesis occur in a renin-independent manner. Despite the common occurrence of PA, little is known about its cellular origins. We have recently identified clusters of cells within normal adrenals that have inappropriate expression of CYP11B2. Through the use of genomic approaches we have demonstrated that these cell clusters have mutations in genes that disrupt normal cellular calcium homeostasis, leading to renin-independent aldosterone production. These findings support the concept that adrenal cell calcium homeostasis is an important regulator of both normal and pathologic production of steroids. In addition, somatic gene mutations that alter intracellular calcium homeostasis and cause renin-independent aldosterone production are quite common, even in normal adrenals. Studies to define the mechanisms causing these dysplastic cells to expand in number and cause PA are underway.