Shy-withdrawn behaviours place preschoolers at increased risk of experiencing adverse developmental outcomes. Positive teacher-child relationships play a protective role against these negative socioemotional outcomes. This study aimed to understand, in-depth, the beliefs, practices and support needs of preschool teachers toward shy-withdrawn children. Thirty preschool teachers of children aged 3-5 years were interviewed, using a semistructured guide. The thematic analysis revealed that most preschool teachers were aware of the main manifestations, transactional influences and consequences of shy-withdrawn behaviours, and of the empirically validated strategies that may be useful to modify them. However, a noteworthy proportion of participants reported misconceptions about the intentionality of shy-withdrawn behaviours, negative emotions and inconsistent or less effective practices. Our findings highlight that strengthening pre-service and in-service training and providing "coaching" to the preschool staff may be helpful to restructure dysfunctional beliefs about shy-withdrawn behaviours, translate developmental knowledge in evidence-based classroom practices and enhance professionals' self-awareness.