<b>Determinants of Academic Performance in Physics of Fourth Year Students in the Catubig Valley National High School, Catubig, Northern Samar for the School Year 2006 2007</b> This study aimed to answer the following questions Determine how each of the following factors, namely study habits, peer group barkada influence, family influence, textbook holdings, lack of interest in the subject had affected the academic performance of the students. Identity which of the identified factors had significantly affected the academic performance of high school students. The research design used in this study was the descriptive method using a questionnaire as the principal instrument in gathering the needed data. The respondents were the fourth year students of the Catubig Valley National High School, Catubig, Northern Samar during the school year 2006 2007. The findings of this study use the following Most of the students or 41 would “sometimes” study their lessons, 31.33 would “rarely” study their lessons, and 26.66 had regular study habits. A significant majority 90 of the students had barkada, only 10 did, not have barkada, 40 of the students would go out with their barkada on weekends and or holidays, 33.33 of the students would go out during off school hours, and 16.66 would go out with their barkada anytime even if they had classes. Majority 90 of the students lived with their family, while the other 10 live with their guardian. Only 3.33 of the respondents had a monthly family income of P30,000.00 or more, 10 had monthly income of P15,000.00 to P19,000.00. 16.660 had a monthly family income of P10,000.00 to P14,000 00, 43.33 had a monthly income of P5,000 00 to P9,000 00, and 26 666 had an income of P5,000. 00 or below every month. Fifty percent of the students were badly affected by the family income every month, the other 50 declared otherwise. Majority 86.66 of the students had a textbook of their own. Only 13.33 shared a book with a classmate. Majority 63.33 claimed that their performance in the subject was not affected by the textbook ratio on the other hand, 36.66 said that their academic performance was affected by the textbook ratio. Majority 53 336 of the students occasionally liked the subject, 40 had moderate liking of the subject, while 6.66 had never liked the subject. Most of the respondents 45 of them got a general average grade in Physics ranging from 80 to 85 , 24.12 obtained a general average grade between 85 to 89 , 20.83 obtained a general average grade range of 75 to 79 , a very small percentage or 9.16 obtained an average grade of 90 or above. The factor that affected most the academic performance in Physics of the students was their level of interest in the subject, while the factor that had the least effect is the book ratio. academic performance, study holistic, per group, family influence 46-51 Issue-2 Volume-1 Lyra Paz P. Lluz