The aim of this study is to investigate the effects of applying the writing letter activity of writing to learn strategies on the English Language Academic Achievement and Attitude level of 11th grade students. The research was carried out with 84 students (43 male, 41 female) at one of the state schools in the Black Sea Region of Turkey. Mixed method was used in the research. A non-equivalent control group model which is one of the quasi-experimental methods was used in the quantitative part of the research. Simple Past Tense Achievement Test (SPTAT) developed by the researcher and Attitude to English Lesson Questionnaire (AELQ) developed by Erdem (2007) were used to obtain the quantitative data. Structured interview questions were asked to the six students chosen from the experimental groups using the maximum variety technique. At the end of the research, it is detected that using writing to learn strategies in English classes makes a statistically significant difference for the benefit of experiment groups on the level of academic success and attitude to lesson.