This chapter considers the planning of interviews with complainants regarding sexual offences. The importance of developing a plan has long been emphasised in the literature surrounding investigative interviews with complainants and witnesses. These interview plans should be informed by three types of information: what is known about the interviewee, what is known about the alleged offence and any background information that could assist the investigation. Information about a complainant that is relevant to an investigative interview can be established by means of a pre-interview needs assessment. Needs assessments are central to the identification of a complainant’s support and communication needs and the first step to ensuring that they are addressed. Information about the alleged offence and relevant background material should, ideally, be kept to a minimum to mitigate the possibility of confirmation bias. This information should then be used to set the objectives for the interview and to inform a series of decisions concerning the conduct of an interview with a complainant. Overall, this chapter argues that pre-interview needs assessments and interview plans are not luxuries to be readily dispensed with when an interviewer is busy. At best, the absence of a needs assessment and an interview plan increases the chances that adult complainants will not communicate their best evidence and at worse it could deny them their right to access justice altogether. Thus, in addition to being a procedural requirement, pre-interview assessments and interview plans are an ethical imperative in jurisdictions that promote victim-centred approaches and trauma-informed practice.