PURPOSE: The research was conducted to investigate the experience of maternal role attainment of mothers of premature infants admitted in NICU and to conceptualize the phenomena. METHOD: The grounded theory method was utilized for data collection and analysis. 8 mothers of premature infants were selected and in-depth interview was performed. Paradigm model was utilized for data analysis and presentation. RESULT: The central category was "unstable maternal identity". The properties of the core phenomena was "ambivalent feeling to baby" "negative emotion" "commitment to baby". The loss of control due to premature delivery was the causal condition. contextual condition was the "perceived threats" due to severity of the premature infant and uncerainty of the baby's life. The mother's health status, economic status, and familial and social support was recognized as intervening conditions during the process of maternal role attainment. The strategic action/interactions were emotion-focused coping, reappraisal of the situation, problem-focused coping, and information seeking. The consequence was the maternal role attainment with competence and expectation. CONCLUSION: The process of maternal role attainment was affected by threats due to severity of the baby and intervening factors and interaction strategy. Further research is recommended to develop adequate intervention method during the process of maternal role attainment.