This study aimed to analyze the use of nominalization in report texts written by
senior high school students, focusing on the types of nominalization used, the
frequency of its occurrence, and the level of lexical density in students' writing.
This research used a qualitative approach with a content analysis method. The
research instrument was documentation, namely ten English report texts written by
11th grade students. The data were analyzed based on Halliday's (1998)
classification of nominalization, which included four types: quality, process,
circumstance, and relator nominalization. The results showed that all types of
nominalization were found, but their usage varied. The process nominalization type
(type 2) was the most dominant (65%), followed by quality (25%), circumstance
(7%), and relator (3%). In addition, the lexical density measurement results based
on Ure’s approach (1971) showed that most of the students' texts were in the high
to very high category. This finding showed that students had begun to show mastery
of academic linguistic features, although there was still a need for explicit learning,
especially on more complex forms of nominalization. This study contributed to the
development of genre-based scientific writing teaching at the high school level.

Keywords: Nominalization, Lexical Density, Report Text, Academic Writing, High
School Students