Epithelial cells form sheets of cells that surround our organs. These cells act as a biological barrier, controlling the passage of ions, water, and nutrients while preventing pathogens from passing between them. Epithelial cells are connected by specialized structures called cell-cell junctions, which include tight junctions (TJs) and adherens junctions (AJs). TJs seal the space between cells and regulate the permeability of small molecules, and AJs mechanically couple cells together. Both of these structures need to be connected to an apical actomyosin array in order to be functional. Much is known about how cells are connected at the interface of two cells (bicellular junctions, BCJs). However, much less is known about how the connection between cells remains intact at the corner where three cells meet, tricellular junctions (TCJs). TCJs are unique sites because they are under increased tension compared to BCJs. In the vertebrate epithelium, several TJ-specific proteins have been identified and shown to be essential for maintaining barrier function. Using Xenopus laevis embryos as a model for the vertebrate epithelium, previous work from our lab identified that an AJ protein, Vinculin, exhibits enriched localization near TCJs. However, whether Vinculin plays a function role in in maintaining epithelial integrity at TCJs remained unclear. In this dissertation, I optimize self-labeling protein tags and a tissue stretching technique for use in Xenopus embryos, and I investigate Vinculin’s role in maintaining junctional integrity and epithelial barrier function at TCJs. First, I establish the use of SNAP- and Halo-tagging in Xenopus laevis embryos for labeling proteins of interest. By adapting SNAP- and Halo-tagging for our model system, we can overcome several limitations that we previously faced. Critically, this approach allows us to brightly label proteins of interest in a wide variety of colors, including red and far-red. Second, I establish the use of a custom-built tissue stretch device that is compatible with live microscopy of Xenopus laevis explants, allowing us to modulate tension without small molecules. Then, I determine the mechanism by which Vinculin maintains TCJ integrity, despite TCJs being sites of increased tension. I show that Vinculin is recruited to TCJs in a mechanosensitive manner by increasing tension using two approaches. I go on to show that Vinculin directly organizes and stabilizes actomyosin, specifically at TCJs. When Vinculin is knocked down, the tricellular TJ protein, Angulin-1, is significantly less stable at TCJs. When challenging embryos with increased tension, TCJs in Vinculin knock down embryos are not able to maintain proper morphology compared to controls. Finally, I show that Vinculin knockdown embryos have significantly more barrier leaks at TCJs than controls. Collectively, the work in this dissertation identifies a novel role for Vinculin at TCJs in maintaining epithelial barrier function and junctional integrity.