The current study investigates the effect of chronological and theoretical birth order on sexual attitudes and behaviors of college students. The effect of the additional independent variables of age, gender and social economic status were also examined. A sexual attitudes and behaviors survey questionnaire will be used to collect data from Year One Science students of Trinity College on their sexual experiences and attitudes. We are trying to determine whether or not a person's birth order had an effect on when that person first became sexually active and how sexually active that person was. It is hypothesized that later- born children will be more liberal in their sexual attitudes and behaviors. This means that they will begin having sexual intercourse at an earlier, be more sexual activate than their older siblings, believe that it is acceptable to engage in causal and pre- marital sex, and more sexual partners. We also predict that males in all birth order categories will be more sexually active than females, and have more liberal sexual attitudes. The condition of the research based on completion of the given questionnaires. A Univariate Tests of Between- Subjects Effects indicates the birth order had a non- significant effect on sexual attitudes of the college students, F (4,54) = 0.631, P > 0.05. Pearson's r Correlation showed that there was a non- significant weak negative relationship between birth order and sexual attitudes (r = -.006, P > 0.05, 2 - tailed). The Independent- Samples T Test indicated that the scores of first-born group (M=112.58, SD= 25.79) was not significantly different from those third born group (M=113.75, SD=19.43) on sexual attitudes (t (32) =.118, P > 0.05, 2- tailed). This rejected our null hypoFinal Year Project that later-borns have more liberal sexual attitudes that first-borns.