Over the past few decades, research has shown that motivation and personality traits have great influence on learning a second or foreign language (L2). The current study reports on the impact of personality traits and ideal L2 self on academic achievement among Turkish university students majoring English as a foreign language (EFL). A total of 102 participants from a major state university in Ankara, Turkey participated in the study. Data were collected through the Ideal L2 Self Scale and the International Personality Item Pool (IPIP). The results of structural equation modelling (SEM) revealed that personality traits accounted for 35% of the variance in academic achievement and that the ideal L2 self explained 37% of the variance in academic achievement of the participants. Findings also revealed that personality traits significantly contributed to the prediction of the ideal L2 self. Gender differences were also found in the ideal L2 self and personality traits of extraversion, openness, neuroticism, and agreeableness. The findings provide insightful implications for language teachers to cater for their students' individual differences, more specifically personality traits, and help them develop ideal L2 selves which will, in turn, serve as a motivation for successful L2 learning.