PurposeThis study aims to explore the relationship between proactive socialization behaviors (PSBs) and work engagement, with a specific focus on the mediating role of social capital resources (SCRs). Additionally, it investigates how proactive personality and perceived organizational support (POS) moderate the organizational assimilation of newcomers in Punjab, Pakistan, through the lens of self-determination theory.Design/methodology/approachA cross-sectional survey design was employed, with data collected from diverse organizations across cities in Punjab, Pakistan, including Bhimber, Gujrat, Gujranwala, Lahore, Jhelum, Kharian, Kotla, Mandi Bahauddin, and Sialkot. A total of 1,000 questionnaires were distributed, resulting in 619 valid responses. The sample primarily consisted of individuals with varying levels of work experience, contributing to the diversity of the data. SEM was utilized to analyze the relationships between the studied variables.FindingsResults indicated a significant positive association between PSBs and work engagement among newcomers. SCRs were found to mediate this relationship, suggesting that proactive behaviors help newcomers accumulate social capital, which enhances work engagement. Moreover, the study reveals that proactive personality and POS significantly moderate the relationship between PSBs and work engagement, with stronger positive associations observed among proactive individuals and those perceiving higher organizational support.Practical implicationsThe study underscores the importance of encouraging proactive socialization behaviors and strengthening organizational support systems to foster newcomer engagement and facilitate successful assimilation.Social implicationsUnderstanding these dynamics can lead to the creation of more inclusive and supportive organizational environments, enhancing both individual well-being and organizational effectiveness.Originality/valueThis research offers new insights into the mechanisms through which PSBs impact work engagement, particularly through the accumulation of SCRs, and highlights the importance of proactive personality and organizational support as moderators.