The way in which students can identify, regulate and manage their emotions can impact not only on their present positive attitude and increased self-esteem, but also on their subsequent professional performance. In this study, 798 pre-service teachers participated, with a mean age of 24.52 years (±5.48). The instruments used were: "Wong Law Emotional Intelligence Scale" (WLEIS-S), "Life Orientation Test Revised" (LOT-R) and the "Rosenberg Self-Esteem Scale" (RSES). The aim was to determine the potential value of optimism and pessimism among the emotional intelligence and self-esteem of pre-service teachers. The results showed that emotional intelligence is related to optimism (R[superscript 2] = 0.352) and moderately to pessimism (R[superscript 2] = 0.148) and self-esteem (R[superscript 2] = 0.135), with a root mean square error of 0.067. The practical consequences showed that emotional intelligence has a strong impact on socioemotional competencies, with optimism versus pessimism acting as mediating variables, which in turn contributes to the self-esteem of future teachers.