The report, released by the government, detailed progress from year eight enrolment and, unlike previous reporting, tracked individual students.
Of the 13,774 students enrolled in Years 12 and 13 in 2017, only 57 per cent completed the South Australian Certificate of Education (SACE).
Education Minister John Gardner said the SACE retention rates identified in the research present "a set of challenges".
“The Liberal Government believes that it is critically important to address these issues," he said.
The completion rate rose from 56 per cent in 2016, when figures showed that 7777 students completed SACE and a further 2488 participated in vocational training.
But the educational outcomes of the remaining 3736, or 27 per cent of students, is listed as unknown.
Gardner said the government will use the data to establish research partnerships.
"Clearly we need to gain a better understanding of why some students are falling through the cracks," he said.
“This research will help us understand the barriers and incentives that are influencing students in making their life choices, and what schools can be doing to facilitate young people into meaningful study or employment."