The major purpose of the study was investigating students' spelling errors in compositions theyrnproduced. To reach this goal instruments such as composition writing; multiple choice test,rnwhich contain three misspelled and a correctly spelt word, having 30 questions were designed;rnand checklist for relative coverage of spelling lessons of grade 12 text book were prepared. Thernsubjects of the study were Yekatit 12 Preparatory School grade 12 students and teachers. Fromrn658, i.e. 14 classes, total population 235, i.e. 5 classes, were taken using purposive sampling.rnThen, systematic random sampling technique was employed to choose 70, i.e. 29.7%, samplesrnfrom 235 students. The selected samples were taken to two classrooms, i.e. 35 in each, andrninvited to write the composition. On the next day the test was administered to the students.rnFollowing the test, 15 students from the samples and four English language teachers wererninterviewed. The errors obtained in the composition and the test were subjected to five majorrncategories, i.e. Addition, Omission, Substitution, Transposition, and Semantically Di.fJerentrnWords. To analyze and interpret the data bothÂ· quantitative and qualitative methods werernapplied In a similar vein analyzed data revealed that 1937, i.e. J3.5%, spelling errors werernfound from 14,357 total number of words observed in the compositions; and from the totalrnnumber of 1033 errors in the test, an individual student, on average, committed14.8 errors fromrnthe 30 multiple choice questions. Of the error types Omission and Substitution took the lionsrnshare. Particularly Vowels are found to be the deficits of students. However, it doesn't mean thatrnthe rest error types have insignificant role in blocking readers from what the students intended tornconvey. Rather, semantically di.fJerent words used in the learners' compositions, especiallyrnhomonyms, ; were found the most problematic parts of the error types at grade 12 level. Inrnconclusion, spelling seems the most neglected skill which both students and teachers give littlernattention. Accordingly, to help students develop their spelling skill much has to be done by bothrnteachers and students. Teachers have to get the courage and motive to design teaching materialsrnand assist their students. Students, on the other hand, should try to use their own effort tornimprove their spelling skill so as to communicate effectively through writing. It should also bernnoted that integrated teaching of pronunciation and spelling has contribution for students'rnspelling improvement. .