This research aimed to identify the factors that influence students to use
code-switching and code-mixing and the impacts of using code-switching and
code-mixing. A survey was conducted as a research approach. This research used
a mixed method between quantitative and qualitative data analysis with two
instruments: a close-ended questionnaire and a structured interview. The
respondent of this research was 47 students from the 4th semester who studied in
English Language Study Program at private universities in Central Java. The
result from the questionnaire showed the highest score appeared in The
Impression of Being Modern (59,6%) factor which influences students to use
code-mixing. For code-switching, the highest score appeared in Clarifying
Intention factor (48,9%). From the interview results, several positive impacts from
code-switching and code-mixing were collected. These results are more
confidence to express thoughts, acquire more vocabulary, get used to writing in
English, find it cool because the text will not be boring, and memorize the English
vocabulary well. Besides, code-switching and code-mixing also impact students'
communication skills.