An external review at Hutt Valley High School prompted by concerns about bullying and student safety suggests problems are isolated and the culture is generally positive.
The review was conducted by the Education Review Office (ERO) and aimed to evaluate the performance of the board of trustees and school management in ensuring a safe emotional and physical environment.
It followed allegations in December which included a sex assault on a student, drug-taking, bullying and intimidation of teachers.
Police became involved following the allegations and five students were referred to the family and youth courts.
The ERO report said interviews with teachers and students had established that a group of students had been chasing members of its own group and allegedly carrying out assaults.
The behaviour had apparently gone on for about two weeks before incidents were reported.
The report said the school had set clear guidelines on what was required in terms of its students' behaviour but a lack of clear procedures in dealing with incidents may have contributed to some parents complaining about the school's handling of them.
It said senior managers had since identified the need to review and improve procedures for managing and reporting complaints and investigations.
The report found no evidence of "ongoing serious misbehaviour" throughout the school apart from the serious December incidents.
"This is not to say that such behaviour may not have occurred in the past or may not occur in the future as it could in any secondary school."
A small number of students had been suspended or expelled this year because of their unacceptable behaviour.
ERO said students needed more opportunity to learn about and practise respect for others and recommended bringing some management policies up to date.
But overall, the students and staff spoken to painted a picture of a "positive and settled" school, the report said.
The school's board of trustees chair Susan Pilbrow said she hoped the review would put an end to bad publicity about Hutt Valley High, some of which was not warranted.
"We are very satisfied with the report, we have always been ready to put out good news about the school.
"Whether the media has been wanting to hear that is always another matter. I don't think the reporting has always been that responsible," she told Radio New Zealand.
ERO plans to carry out another review of the school in the first term of next year.