Molecular mechanisms which stabilize dendrites and dendritic spines are essential for regulation of neuronal plasticity in development and adulthood. The class of Nogo receptor proteins have been shown to have roles in restricting plasticity after injury, as well as in regulating experience- and activity-induced plasticity. Here we investigated the role of the Nogo receptor homolog NgR2 in structural plasticity in a transgenic mouse line null mutant for NgR2. Using Golgi-Cox staining to analyse morphology, we show that loss of NgR2 alters spine morphology in adult CA1 pyramidal neurons of the hippocampus, significantly increasing mushroom-type spines, without altering dendritic tree complexity. Furthermore, this shift is specific to apical dendrites in distal CA1 stratum radiatum. Behavioural alterations in NgR2-/- mice were investigated using a battery of standardized tests and demonstrated that whilst there were no alterations in learning and memory in NgR2-/- mice compared to littermate controls, NgR2-/- mice displayed reduced fear expression in the contextual conditioned fear test, and exhibited reduced anxiety- and depression-related behaviours, accompanied by normal basal stress hormone levels. This suggests that the loss of NgR2 results in a specific phenotype of reduced emotionality. Additionally, investigations of the impact of loss of NgR2 on other plasticity mechanisms demonstrated that NgR2 is not required for normal adult hippocampal neurogenesis, nor does it appear to regulate or crosstalk to MAPK kinase signalling in the hippocampus. We conclude that NgR2 has role in maintenance of mature spines and may also regulate fear and anxiety-like behaviours.