The psychological characteristics that new recruits bring when starting military basic training (MBT) may help or hinder successful completion rates. The first part of this study explores how psychological characteristics assessed at the start of MBT influence retention and performance outcomes upon completion. At the start and upon completing MBT, a sample of 204 UK male Infantry recruits undergoing a 26-week Combat Infantryman’s Course were assessed on personality traits (psychoticism, neuroticism, and extroversion); a set of relevant cognitions (i.e. effortful control); motivation (i.e. internalization of military core values); and an assessment of mentally tough behavior. Recruits who successfully completed MBT were significantly higher in age, psychoticism, and mentally tough behavior. The second part of the study explored how MBT influenced these variables across time. A subsample of 132 male Infantry recruits that passed basic military training first time were analyzed. Across the 26-week course, there was a significant increase in extraversion, and a significant decrease in neuroticism, and external regulation. Results differed slightly when we removed the lowest passing group from the analysis and whether MANOVA or Logistic Regression analysis was used. Results indicate that what you bring to the table will influence pass and retention rates.