Choosing a spouse is one of the most important selections of a person, but the illogical beliefs about the spouse selection can challenge the marriage process of girls and boys; thus, this correlational study was conducted with the purpose of comparing and predicting the illogical beliefs about the spouse selection based on the mental will-being, personality organization, and attachment styles among the students in a comparative manner. The population was all the single students of Payam Nour University in the city of Talesh in the academic year 2016-2017 and 300 students were selected by the simple random sampling. The revised adult attachment scale, the attitudes towards spouse selection scale, the Kernberg's inventory of personality organization, and the mental well-being scale are used for collecting the data. The data were analyzed by the multivariable analyze of variance, Pearson correlation coefficient, and stepwise multiple regression. The findings showed that there is not a meaningful difference between girls and boys in terms of the illogical beliefs about the spouse selection, mental well-being, attachment styles, primitive psychological defenses, and identity confusion, except reality testing. In addition, according to the findings, the variables of mental well-being, secure attachment, reality testing, and identity confusion can explain 18. 6% of the variance of illogical beliefs about the spouse selection. This study suggests that the training of and intervention in mental well-being, personality organization, and attachment styles of girls and boys are an effective way to decrease their illogical beliefs about the spouse selection and facilitate their marriage.