Menarche is a key pubertal change for girls which is accompanied by different psychosocial changes, both pleasant and unpleasant, shaped by cultural and societal influences. This study aimed to examine: (1) the main source of information about menstruation before menarche among Croatian girls, (2) to whom girls confide about menarche and how they perceive the response of the significant other, (3) the role of preparedness and response of significant other for emotional reaction to menarche in adolescent girls. Postmenarcheal girls (N = 246) from primary and secondary schools from Croatia filled out the Expected/Experienced Emotions related to Menarche Scale measuring pleasant and unpleasant emotional reactions; Preparedness for the Menarche; Significant Other’s Responses to Girl’s Menarche Checklist measuring informational support and positive emotional responses; and a set of specific questions. For most adolescent girls, the mother is both the main source of information (97.2%) and the first person to confide about the menarche (83.7%). Girls perceived the response of the significant other more as informational support (such as providing information on the use of sanitary products) than as positive emotional response. However, the positive emotional response of the significant other, together with higher levels of preparedness, predicted higher levels of girl’s pleasant personal experience at menarche. Psychoeducation should be focused both on girls and their mothers so they could know how to prepare their daughters timely and respond positively to this important event.

menarche, menstruation, preparedness, mother, puberty