Growing Up in Australia, the Longitudinal Study of Australian Children (LSAC), is now in its 11th year with the “Baby” cohort currently aged 10-11 and the “Kinder” cohort aged 14-15. Six waves of data have been gathered, with the seventh wave now under development. Across these data collection waves, content has been centred around three key developmental areas; health and physical development, social and emotional functioning, and learning and cognitive ability. Whilst these developmental domains have remained consistent, the content within these domains has grown with the children, both in relation to content quantity and choice of measure to ensure age-appropriateness. The length of the study child interview has increased gradually since the children first became study informants in Wave 3 and is now equal to the parent interview. This increase is partly due to the need to add in new measures, additional to key longitudinal constructs, that are vital to capture at particular ages and during specific developmental phases. For example, to effectively cover the transition into adolescence content related to antisocial behaviour and romantic relationships was added. Including such content seems simple in itself, but there have been significant flow-on effects to manage in relation to various aspects of the study, such as methodology, respondent engagement, respondent protection, communication with study children and parents, and interviewer training and procedures. For example, much of the content introduced in early adolescence is highly sensitive in nature. A key concern is about protecting informants from the potential harms of asking such questions. However, other issues also arise such as how much information to give parents about the sensitive questions their children will answer and how to support interviewers. In this paper, issues such as these that have arisen during key developmental phases will be examined, including those to be faced in future waves of LSAC as children transition into adulthood. In addition, the approaches taken to address these issues will be discussed.