This dissertation focuses on the role of family and social relationships in individuals’ reproductive careers during the fertility decline in Soviet Ukraine from around 1950 to 1975. These three decades after the Second World War signified the end of the First Demographic Transition in Ukraine and other European republics of the Soviet Union, and some even define the period after the 1960s as the start of a latent depopulation in this part of Europe. However, this fertility decline that had already begun to manifest itself in the early 1920s gained speed within only a few generations as those who were born in families of six siblings in the 1920s and 1930s had only two children themselves in the 1950s, the 1960s and the 1970s. Previous research has discussed these demographic changes on a macro-level for the Soviet and post-Soviet periods by typically linking these changes to the processes of modernisation and transformation. However, this singular focus on structural changes ignores the fact that relationships between people also adjust to politico-economic changes according to the social and family values that al- ready exist in society. As a result, old and new social (in)equalities, both outside and within the household, (re-) emerge alongside the politico-economic modernisation, which, in tandem, contribute to the formation of different demographic realities on a micro-level and different fertility trends on a macro-level. In this respect, social relationships should be seen as playing an intermediary role in the interplay between the formation of interpersonal inequalities and the politico- economic reality. Because they surround our everyday lives and choices, social relationships form a coherent social structure that helps us to interpret, to under- stand and to adjust to everyday reality, including state legal regulations, political ideology, and economic crises. The primary aim of this dissertation is to study the effects of family relationships and their continuities on changes in reproductive behaviour through a comparative regional perspective in Ukraine during the post-war fertility decline.The role of social relationships in reproductive behaviour is particularly important in the specific context of Ukraine as well as in the broader context of Eastern Europe, where family relationships have provided welfare in critical situations, such as childbearing, childcare and elderly care, both in the past and today. Sim- ilar to Southern Europe, the prevalence of strong family ties in Eastern Europe is also often connected to the high fertility rates in the pre-transitional context and to the rapid fertility decline to the lowest-low level in the 1990s and 2000s. The lowest-low fertility phenomenon is often referred to as a paradox of strong family and low fertility. Moreover, in the context of Ukraine, where regional dif- ferences remain pronounced in many aspects of social life, regional variations in fertility could also be linked to local family values. Considering this, the main research questions that I address in this dissertation are the following: (1) How did family and social relationships influence individual reproductive careers in Soviet Ukraine from around the 1950s to the 1970s? (2) How can local family systems and their associated power dynamics and social interdependencies help to understand fertility decline in Soviet Ukraine? Focusing on these post-war decades is also relevant for our understanding of historical and contemporary fertility decline in this part of Europe because these three decades were significant for the beginning of the Cold War, general liberalisation of the regime and the introduction of some family policies that are still enacted today. On the theoretical level, I frame the empirical analysis of family and social influences on individual reproductive careers in a broader framework of local con- tinuities in family relationships and values, the so-called family systems. In this respect, individual reproductive careers are studied as processual characteristics of reproductive behaviour and long life experiences and include such life events as marriage, entrance into parenthood, abortion and birth control, and transition to second birth. By social influences I understand the ‘process by which attitudes, values or behaviour of an individual are determined by the attitudes, values or behaviour of others with whom he or she interacts’ (Bernardi, 2003, p. 535). I examine different patterns of social relationships, such as those between spouses, generations, siblings and peers. Based on the social influences stemming from family and social relationships, I try to characterise different power relationships and other social interdependencies underlying these relationships, which I then connect to the context of local family systems. On the methodological level, this study is based on the analysis of various qual- itative methods, such as in-depth biographical interviews, life history calendars (LHC) and family photographs. The interviews were collected in two Ukrainian borderland cities: Lviv in western Ukraine and Kharkiv in eastern Ukraine. These sites allowed me to compare how family relationships were historically organised in Ukraine and how they actually shaped the informants’ reproductive decisions. This study also uses archival demographic data and secondary ethnographic materials as supplementary sources. The empirical findings of this dissertation discuss different transitions of individual reproductive careers, namely marriage, entrance into parenthood, birth control and abortion, and transitions to second and later births, all of which I discuss in the context of family and peer relationships. In Soviet Ukraine, the transition to marriage was characterised by strong parental control over men’s and women’s pre-marital practices and sometimes also marital decisions. This strong parental control before marriage was not without consequences, as it seems to have created an imaginary dependency of children on their parents not only be- fore but also after marriage, which I associate with the persistence of paternalistic intergenerational values in family relationships in the two localities. Similarly, the entrance into parenthood was also surrounded by frequent parental assistance, particularly when a couple tried to postpone their entrance into par- enthood. This pattern was also reinforced by the social learning from peers among the Kharkiv informants and social contagion from siblings(in-law) among the Lviv informants. That said, the actual decision to give birth was connected to the ex- pectations of help with childcare in the future. In this respect, I observed that if after the marriage a couple resided separately from their parents, they would also take greater responsibility for childcare, and grandparental support became an additional and temporary option, as it often was in Lviv. However, when spouses resided with either set of parents, they also tended to rely more on the parents in terms of childcare, which I more often observed in Kharkiv and less in Lviv. These differences in dynamics of spousal and intergenerational relationships between the two localities became even more pronounced around abortion and birth control decisions and their practices after first birth. Spousal cooperation in birth control decision-making played an important role in how women exercised their agency in these decisions and which birth control methods the couple used and how effectively they used them. In couples where spouses communicated about birth control and abortion decisions, the women had fewer abortions, as was often the case in Lviv. These women did not feel the need to exercise their agency, as the husbands took over the responsibility of both birth control and abortion. When abortion was practiced as a routine method to limit family size, spouses did not communicate about birth control and abortion, as was the case in Kharkiv. In this situation, birth control was the husband’s responsibility and abortion was the wife’s. These women sought abortions to fulfil their own goals and, at the same time, to maintain the dominant patriarchal order in marital relationships as they understood it. These differences in spousal cooperation with regard to birth control seem to have had direct implications for the transition to second and later births in the two localities. In Lviv, spouses continued to negotiate the timing of second and third births and the childcare arrangements, while still mainly relying on each other in these matters. In doing so, the Lviv informants often adopted a traditional male-breadwinning model, which allowed spouses to share the costs of childcare: husbands were responsible for material costs and wives for the emotional and instrumental costs. However, some women resumed working part-time or worked on jobs with more flexible working schedules after their child’s birth, and then spouses divided the material and instrumental costs of childcare more equally and without a traditional gender bias. In either case, the accumulated costs of childcare were often shared between spouses. This strategy often allowed couples to combine childcare after their first and second/third child, which seems to have been reinforcing for many couples in Lviv to adopt a shorter birth spacing strategy. In Kharkiv, in contrast, the timing of second and later births and childcare were mainly the women’s responsibility. Some continued to rely on grandparental support even after starting to reside separately. However, this support was not always available due to different factors such as the few possibilities for multi- generational co-residence or parental health issues. When women received little intergenerational and spousal support, they tended to delay transition to second birth until they felt more secure. Additionally, women in Kharkiv seem to have learned from each other’s experiences about the benefits of this strategy. As such, the adoption of the waiting strategy seems to have resulted in a more prolonged interval between first and second births, sometimes ten to fifteen years, which in other studies is defined as postponement as opposed to spacing. However, those women who did not meet the deadline for parenthood because they were still feeling too insecure to proceed with another birth never had a second child. Overall, my findings illustrate that the ways in which family relationships were organised over the life course formulated different responses in the two local- ities to the emerging socio-economic conditions. Subsequently, these differences in responses were reflected in regional reproductive strategies. I suggest that these differences in responses have to do with the intrafamilial dependencies in the two localities: more couple-oriented (horizontal intrafamilial interdependen- cies) in Lviv and generations-oriented (vertical intrafamilial interdependencies) in Kharkiv. I also observe continuity in these two social interdependencies with the historical family systems and the intrafamilial (in)equalities produced within them in the past, namely a mix of nuclear-stem family system in Lviv and a joint family system in Kharkiv. In the early life, strong intergenerational connections characterising both family systems seem to have promoted early and universal entrance into marriage and parenthood in the past and during the Soviet time. Additionally, the Soviet family policy adopted many of these paternalistic and pronatalist values on the level of legal regulations, which meant that this re-productive ideology was reinforced within and outside the family. In later life, however, the intrafamily interdependencies start to differ in the two contexts, and this aspect is crucial to understand regional patterns in fertility decline. During the Soviet time, even though socio-economic constraints created more or less sim- ilar structural uncertainties in the both localities, these structural factors did not equally challenge intrafamilial interdependencies between spouse and generations. Subsequently, these local intrafamilial interdependencies resulted in different re- productive strategies on the micro-level and in their reflection on the macro-level fertility trends. Altogether, these findings provide a fruitful ground for formulating future hy- potheses to be tested on larger and representative population samples. They also formulate important clues for policy makers by suggesting that a more relativist perspective that incorporates intrafamilial social inequalities and communication strategies is needed to regulate the issues of fertility decline and subsequently the process of population ageing, the latter of which may soon become a vital issue in this part of the world as well.