Primary Sjögren's syndrome (pSS) is a complex disabling systemic autoimmune disorder. The hallmark of pSS is the T-cell-mediated hyperactivation of B-cells, evolving from asymptomatic conditions to systemic complications and lymphoma development. On tissue level, the typical feature is the lymphocytic infiltration of the salivary gland by B-, T- and antigen presenting cells, as mirrored by the diagnostic cornerstone role of minor salivary gland (MSG) biopsy. B-cells show multiple possible roles in disease pathogenesis, from autoantibody production, to antigen presentation, and cytokine production. B-cells hyperactivation is supported by genetic risk factors, T-cell dependent and independent mechanisms, and the presence of different pathogenic B-cell subsets must be reminded.Many aspects have been investigated in the last year regarding genetic and epigenetics, B- and T-cell role in pSS pathogenesis, their interaction with salivary gland epithelial cells (SGECs) and in their direct or indirect use as biomarkers and predictors of disease development, activity, and lymphomagenesis.In this review, following the others of this series, we will summarise the most recent literature on pSS pathogenesis and clinical features focusing in particular on new insights into pSS molecular stratification and therapeutic advances in the era of precision medicine.