This review paper explores the role of individual differences in second language vocabulary learning, focusing on three key factors: out-of-class exposure (e.g., viewing TV, playing video games and listening to songs), strategic vocabulary learning, and motivation. Individual differences significantly impact vocabulary learning, making it crucial to understand how these factors contribute to learning outcomes. Yet, previous reviews have mainly overlooked out-of-class exposure in their discussion of individual differences. The current review shows that the three factors can have a positive effect on lexical development. There are some points to consider such as the need for a large amount of input for out-of-class exposure to be effective. Additionally, the review shows that both motivation and self-regulation are important for vocabulary learning and that they are positively related to vocabulary knowledge. It shows that more self-regulated and motivated students tend to have significantly larger and more developed vocabulary knowledge. By synthesizing findings from empirical studies on individual differences and vocabulary learning, this review provides insights into making vocabulary learning more effective. [Note: The issue number (3) shown on the PDF is incorrect. The correct issue number is 2.]