In recent times, Indian IT companies have been facing high attrition rates, especially with young employees having three to seven years of experience. Therefore, this study develops and tests a dynamic model of brand-endorsed employee engagement (EE) and employee retention (ER). Particularly, the carryover and temporal effects of the relationships and constructs are studied to understand how employee behaviour evolves over time. Using two waves of longitudinal data gathered from young employees ([Formula: see text]) of Indian IT companies, the proposed conceptual model is investigated to test the temporal differences in the relationships between internal employer branding (IEB), organisational commitment, EE and ER. Additionally, the impact of employer internal social media usage on the relationships is also examined as an effective human resources (HR) intervention in the evolution process. The findings show that excluding the organisational commitment to EE relationship, the other two relationships between IEB to organisational commitment and EE to ER become stronger over time. Interestingly, while internal social media usage does not exhibit direct effect on organisational commitment or ER, it is instrumental in influencing IEB perception and EE during subsequent periods. Overall, this study offers directions to HR managers in the services sector on how to effectively use social media to engender engagement in employees and ultimately, enhance their intention to stay.