In this 2-part article, the authors review the primary cicatricial alopecias. Primary cicatricial alopecia can be defined as predominantly lymphocytic, neutrophilic, or mixed based on the nature of the follicular infiltrate that is present around affected hair follicles. Lymphocytic primary cicatricial alopecias include chronic cutaneous lupus erythematosus (discoid lupus erythematosus), lichen planopilaris, classic pseudopelade of Brocq, central centrifugal cicatricial alopecia, alopecia mucinosa, and keratosis follicularis spinulosa decalvans. In this first part, the authors summarize the classification, epidemiology, diagnostic approach, and patient management of lymphocytic cicatricial alopecias. In part II, the authors will focus on neutrophilic cicatricial alopecias and mixed cicatricial alopecias.