Dendritic spines are the predominant site of glutamatergic inputs throughout the brain. Regulation of spines is therefore critical for refining cortical networks. This research sought to define mechanisms for determining spine fate during developmental synapse remodeling. The central hypothesis is that NrCAM requires intracellular interactions within the spine to promote Semaphorin3F receptor clustering and spine retraction, through binding to the actin adaptor AnkB and microtubule binding protein DCLK1. I have delineated intracellular binding partners of NrCAM in synapse-enriched cellular fractions. I made a mutation in NrCAM that disrupts binding to AnkB and DCLK1 and perturbs Sema3F holoreceptor functioning. I demonstrated that chemical disruption of microtubules affects spine morphology and response to Sema3F. Finally, I have shown in vivo mutations affecting AnkB result in altered spine densities. The findings provide insight toward understanding the molecular mechanisms of dendritic spine remodeling and the pathology of neurodevelopmental disorders involving dendritic spine anomalies.