The aim of this study is to investigate the structure and complexity of emotional states experienced by young musicians before entering the stage and to explain the influence of emotional beliefs on their pre-performance emotions. Emotions were elicited with a guided imagery induction, where 222 students aged 9- to 12-years-old recalled their most recent concert memory. They described their emotions on the list of 18 emotions (nine pairs of contrary emotions) and answered three questions measuring music performance anxiety (MPA) beliefs: MPA utility beliefs, MPA regulation beliefs, and audience attitude beliefs. The cluster analysis results show the complexity and multiplicity of emotional states reported by young musicians. Five emotional profiles vary from negative emotions of fear and sadness (High MPA) through a mixture of positive and negative emotions (Moderate MPA, Hesitation, Ambivalence) to positive emotions of confidence, courage and happiness (Composure-Confidence). Beliefs that MPA has negative impact on performance, beliefs of inefficacy in managing MPA and perceived audience pressure rather than support were related to High and Moderate MPA profiles. Practical implications for music education are discussed.