The purpose of the present study is to compare ability estimations obtained from computerized adaptive testing (CAT) procedure with the paper and pencil test administration results of Student Selection Examination (SSE) science subtest considering different ability estimation methods and test termination rules. There are two phases in the present study. In the first phase, a post-hoc simulation was conducted to find out relationships between examinee ability levels estimated by CAT and paper and pencil test versions of the SSE. Maximum Likelihood Estimation and Expected A Posteriori were used as ability estimation method. Test termination rules were standard error threshold and fixed number of items. Second phase was actualized by implementing a CAT administration to a group of examinees to investigate performance of CAT administration in an environment other than simulated administration. Findings of post-hoc simulations indicated CAT could be implemented by using Expected A Posteriori estimation method with standard error threshold value of 0.30 or higher for SSE. Correlation between ability estimates obtained by CAT and real SSE was found to be 0.95. Mean of number of items given to examinees by CAT is 18.4. Correlation between live CAT and real SSE ability estimations was 0.74. Number of items used for CAT administration is approximately 50% of the items in paper and pencil SSE science subtest. Results indicated that CAT for SSE science subtest provided ability estimations with higher reliability with fewer items compared to paper and pencil format.