Objective: Happiness, as one of the most important aspects of students’ mental health has a significant influence on their social growth and personality development, and it has always been of interest to the researchers in different fields of psychology.
Methods: In this study, the method of correlation was used and the population of study was all students of Farhangiyan University of Guilan during the academic year 2013-2014 which included 1777 students. Among this population, a sample of 250 students (including 149 women and 101 men) was selected and studied using stratified random sampling method. The student adaptation to college questionnaire (SACQ), interpersonal forgiveness scale (IFS) and Oxford happiness questionnaire (OHI) were used for data collection. The resulting data were analyzed by applying multivariate regression analysis method in SPSS vs. 19.
Results: The results showed a significant and positive relationship between adaptation to college and interpersonal forgiveness with the happiness (at the level of P<0.01) and it was concluded that these variables, in combination with each other, were able to account for 58% of the variance of happiness. Among the independent variables, the component of social adjustment had the greatest role in the prediction of happiness among the students. 

Conclusion: Since the variables of adaptation to college and interpersonal forgiveness are suitable predictors for happiness, consideration of these variables in the students’ mental health promotion programs is highly recommended.