The researcher focused on three questions to be analyzed; (1) Is there any correlation between students’ locus of Control and writing skill? (2) Is there any correlation between students’ transitional devices mastery and writing skill?, and (3)Is there any correlation between students’ locus of Control, transitional devices mastery and writing skill?. After that, the result of the research was used to find out its implication to a lesson plan. The research used a quantitative method that is correlation study. It was conducted  in  SMA  NKebakkramat  in  the  academic  year  of  2016/2017.  The sample of the research was from class XI IPA 5 of SMA N Kebakkramat which consisted of 30 students. To obtain the required data, the researcher used questionnaire of locus of control  to  measure  participants’  level  of  LOC,  transitional  devices  mastery multiple choice test, and writing test of descriptive text. For analysis of data, the researcher used Pearson Product Moment Correlation and Multiple Correlation. The result revealed that (1) there is a significant positive correlation relationship between locus of control (LOC) and writing skill (Y). The correlation coefficient (rxy) between student’s locus of control (X1) and writing skill (Y) is 0,42 and ro  is higher that rt  or 0.42 > 0.36. (2) There is a significant positive correlation relationship between transitional devices mastery, and writing skill. The correlation coefficient (rxy) between student’s transitional devices (X2) and writing skill (Y) is 0.52 and ro  is higher that rt  or 0.52 > 0.36. (3) There is a positive correlation between students’ locus of control, students’ transitional devices mastery simultaneously toward students’ writing skill. The correlation coefficient (Ro) between students’ locus of control (X1), students’ transitional devices (X2) simultaneously and writing skill (Y) is 0.57 and Fo  (6.90) is higher than Ft(2.27) for ? = 0.05 is 3.35. The students’ locus of control (X1) gives 11.96?fective contribution to writing skill (Y) while the students’ transitional devices (X2) gives 21.85% to writing skill (Y). As the result, the total effective contribution of two independent variables to the dependent variable is 33.81%. It means that the increase of students’ locus of control and students’ transitional devices mastery will be followed by the increase of students’ writing skill. As a conclusion, it shows that students’ locus of control and students’ transitional devices mastery influence the students’  writing  skill  of  33.81%  while  other  factors  contribute  66.19%  of students’ writing skill.