Newcomer turnover is a major cost to organizations, and the quality of new employees' experiences in the first few months is critical in determining whether they decide to stay or leave. In a study that focused on the first stage of newcomer socialization, we investigate the impact of perceptions of social validation from the team and the team leader, and perceived fairness of treatment on newcomers' identification with their work team and the organization, specifically measuring the group self-investment components of identification. The mediating role of these levels of group self-investment and of the imbalance (i.e. difference) between levels of self-investment on turnover intentions was also tested. New staff (N=569) joining a large public-sector organization completed a questionnaire about their socialization experiences in their first 6 months of their employment. Structural equation modelling revealed that social validation by the team and team leaders, and fairness of treatment, predict increased investment with the organization and with the team. Organizational-level self-investment and an imbalance in favour of investment with the organization over that of the team mediated decreases in turnover intentions. We conclude that organizations should provide newcomers with validation that promotes identification with their organization during this critical stage of socialization.