The feeling that an attachment figure is available and responsive when needed (also referred to as attachment security) is an important factor in the activation of the fear system such that attachment security is thought to decrease fearfulness. To date, no study has examined whether attachment security causes decreased fearfulness. Adult attachment researchers have used priming techniques to investigate whether increased security causes improvement in various adult psychosocial outcomes (for a review see Mikulincer & Shaver, 2007) and priming techniques have been useful in research with children. As such, attachment security priming may be a valuable research tool to determine whether attachment security reduces children's fear reactions. In addition, mothers' negative and unsupportive responses to children's negative emotions are associated with poor socio-emotional outcomes for children (Eisenberg et al., 1998). As such, maternal negative and unsupportive responses may be linked to children's fear responses. Child temperament is also an important factor in children's fear reactions such that temperamentally more fearful children may be more influenced by the effects of attachment security and maternal responses to child distress. The present study was designed to extend attachment security priming methods to research with children between 6- and 7-years-of-age by employing a multi-method experimental approach to examine (a) whether experimentally induced attachment security causes less fearful reactions to fear-inducing tasks in children, and (b) whether maternal emotion socialization is associated with the fear reactivity of children randomly assigned to the neutral control group. Additionally, the present study also seeks to examine (a) whether the effects of experimentally-induced attachment security on children's fear reactions vary as a function of children's temperamental fearfulness, and (b) whether the link between maternal emotion socialization and children's fear reactivity is moderated by children's temperament fearfulness. After having been exposed to subliminally presented attachment security picture primes, six- and seven-year-old children had lower physiological fear reactions during observations of fear-inducing pictures than children exposed to subliminally presented happy or neutral picture primes. There were no links between maternal responses to child distress and children's fear-reactions. Results did not differ as a function of child temperamental fearfulness.