This report describes a study that analysed Wellbeing@School student and teacher survey data from 400 New Zealand schools. The study explored the following questions: (1) Are there school practices associated with higher levels of student wellbeing or lower levels of student aggressive behaviours?; and (2) Are some school or student characteristics more likely to be associated with high or low wellbeing or student aggressive behaviours than others? The study examined the relationships between four measures created from Wellbeing@School data: (1) a "student wellbeing" measure; (2) a "student aggressive behaviours" measure; (3) a teacher measure of "school-wide actions"; and (4) a teacher measure of "teaching for wellbeing." Some of the findings from this research have previously been summarised in the infographic report "Making a difference to student wellbeing" (Lawes & Boyd, 2017). This current report provides the methodological details behind the infographic report and also extends the findings. [For "Making a Difference to Student Wellbeing," see ED598183.]