The present study focuses on the effectiveness of interactions with callers to a helpline as perceived by the helpline volunteers. Applying a qualitative methodology, we analysed 12 descriptions of what the volunteers considered to be the most helpful calls they could reconstruct from memory, and the factors they attributed to the successful outcomes of the interactions. The findings revealed crisis intervention, namely the provision of short-term help in stressful experiences occasioned by threatening events, to be the type of interaction chosen in almost all the cases rather than ongoing emotional support. The portrait of a successful interaction that emerged from the data can be described as follows. The volunteer succeeds in establishing an egalitarian rapport with the caller, focuses the conversation on a single problem, manages the conversation while adapting the pace and duration to the caller's needs, creates a supportive environment that affords the caller emotional safety, and employs a variety of strategies in order to produce an emotional, cognitive, or behavioural change in the troubled caller's state. (Contains 3 tables.)