Although cross-sectional studies have explored the correlation between envy and loneliness, few longitudinal studies have investigated the bidirectional association between envy and loneliness at both trait and state levels. Here, through a longitudinal study and a daily diary investigation, we examined the interrelationships between envy and loneliness at both trait and state levels. In study 1, 288 college students answered the Dispositional Envy Scale (DES) and UCLA Loneliness Scale (UCL-8 Scale) twice with a one-year interval. The results of cross-lagged analysis indicated that dispositional envy could predict trait loneliness, while not vice versa. In study 2, using the adapted items form DES and UCL-8, a 14-day diary survey from a sample of 195 college students was conducted to investigate the interrelationship between state envy and state loneliness. The results of multivariate latent growth models and hierarchical linear models indicated that state envy could positively predict state loneliness and vice versa. Taken together, these findings uncover the bidirectional relationship between envy and loneliness at both the trait and state levels.
