The study examined whether psychological birth-order positions have an association with personality types. A total of 378 participants were recruited from a Myers–Briggs Type Indicator (MBTI) fan site and asked to report their psychological birth order. On the basis of their MBTI, all participants belong to four psychological types (introvert vs. extravert, sensor vs. intuitive, thinker vs. feeler, and perceiver vs. judger). Chisquare analysis revealed that only children (defined as children who do not have siblings less than 5 years younger or older) have an increased chance of being introverted compared to other birth-order positions. Furthermore, middle children have a significantly decreased chance of being introverted and a significantly increased chance of being feelers than other categories of birth order.