Women's needs after childbirth are varied and numerous, and the weeks and months following birth are crucial for both mother and baby. Many women experience emotional issues after childbirth, and some of these complications may persist for a prolonged time period. The trickle-down effects of mothers who do not feel mentally well are significant, as reduced mental wellbeing is associated with poor health outcomes for their babies and families. Despite these ramifications, the postnatal period is often 'eclipsed' by the attention paid to the antenatal and intrapartum periods, and the health needs of postnatal women are often not addressed in practice or research. While a considerable volume of work has focused on postnatal depression (PND), only 12-14% of women fall into this diagnostic category, and there is a lack of research examining the postnatal mental wellbeing of the remaining majority. Research in a Tasmanian context is particularly scarce. For these reasons, determining how mental wellbeing can be promoted for women in this context is the focus of this study. To gain a better understanding of what influences new mothers' ability to cope, a longitudinal, phenomenologically-informed study was conducted in northern Tasmania. Purposive sampling was used to recruit 13 first-time mothers, and a series of four in-depth interviews was undertaken with each participant over the course of her first year of motherhood. The interviews were digitally recorded and transcribed verbatim, and then analysed using a modified version of van Manen's analytic strategy. After analysis, overarching themes from each set of interviews emerged as an illustration of the commonalities in the lived experiences of first-time motherhood in Tasmania. These themes were utilised to gain improved understanding of how mental wellbeing in new mothers can be promoted. The findings of this study suggest that new mothers face challenges in coping, even outside the diagnostic category of PND. Some sources of struggle for these women included learning to breastfeed, adjusting their self-identities to include being a mother, shifting their priorities, and juggling the competing new demands in their lives. Participants also noted a lack of maternal-focused health care once their babies were born. None of the 13 participants in this study were diagnosed with PND, however each of them recounted struggles, emotional lability, and difficult periods as they adapted to their new lives as mothers. Certain influences were shown to mitigate the challenges they experienced, including multiple forms and sources of support, as well as fostering self-efficacy and time for self-care. This study therefore gives voice to the majority of women who do not become clinically depressed in early motherhood, but face struggles as they find a new balance and adapt to life during their first year with a baby. This research articulates the breadth of needs women have over the course of the first year after childbirth from a mental wellbeing perspective, and how these needs change over time. By examining how these needs can be addressed, strategies for promoting mental wellbeing in this population can be developed. An empirically based health promotion model was developed to articulate strategies to promote maternal mental wellbeing for new mothers. Tasmania lacks a comprehensive program of care for women in the postnatal period, and this research can contribute to the development of informed policies to provide improved emotional support to future first-time mothers.