Introduction. The article is devoted to the legal aspects of mobilization and social (civic) responsibility, their features and manifestations during the period of martial law. The interrelationship between them and the manifestations of the processes associated with them is also analyzed. In addition, it is emphasized that mobilization and civic responsibility are one of the key components of successful defense of the Motherland. Summary of the main results of the study. Mobilization processes and subsequent military service during martial law are regulated by the legislation of Ukraine, in particular, Constitution of Ukraine, the laws «On military duty and military service», «On mobilization training and mobilization», «On the defense of Ukraine», «On the legal regime of martial law», «On the number of the Armed Forces of Ukraine», the Regulation on the completion of military service by citizens of Ukraine in the Armed Forces of Ukraine, approved by the Decree of the President of Ukraine dated 10.12.2008 № 1153/2008. Approaches to the definition of the concept of «mobilization» from the perspective of legislation and from the point of view of scientists have been analyzed. The definition of the concept of «martial law» and the number of possible numbers in the usual regime and in a special state have been determined. It is noted that the constitutional obligation applies to all citizens of Ukraine, both men and women. At the same time, the percentage ratio of the number of representatives of the female and male sexes is demonstrated with the help of a diagram. The diagram also shows the change in the number of the Armed Forces of Ukraine before and after the full-scale invasion of the russian rederation into the territory of our Motherland. The concept of «civic responsibility», as a form of social responsibility, is defined, which is considered by scientists in different ways, but directly relates to the personality of a citizen. Next, the relationship between civic responsibility and mobilization, how they influence each other, is considered. It was determined that the formation of civic responsibility among representatives of the country's population affects the desire for voluntary military service during the mobilization period, and later – for contractual military service. In addition, the author's opinion regarding the expression of the fact of the formation of civil responsibility of the population during their stay in the rear was presented. Conclusions. Reasoned conclusions based on the presented material about the specifics of the definitions of the concepts «mobilization» and «civic responsibility»; on the specifics of the fulfillment of the constitutional duty to protect the Motherland by the citizens of the country, the total number of the Armed Forces of Ukraine, which increased by 2.7 times during the full-scale invasion of the Russian Federation on the territory of Ukraine, which is a reason to claim that the citizens of Ukraine have developed civic responsibility and joined the ranks of the Armed Forces of Ukraine and other military formations not only as a fulfillment of a constitutional duty. In addition, the author emphasizes that the formation of this type of responsibility consists not only in readiness to protect the Motherland, but also in other aspects, in particular, volunteering, helping and supporting military personnel and their families, participation in events, observance of public order, especially during the wartime period state.