Title: Bordered Floer homology and splicing knot complements Abstract: We use bordered Floer homology to study 3-manifolds obtained by gluing together two knot complements (gluing meridian to longitude). If the knots are non-trivial knots in S^3, we show that the Heegaard Floer homology of the resulting manifold has rank greater than one. By extending this approach to knots in arbitrary three manifolds, we hope to obtain a new proof of Eftekhary's claimed result that a manifold whose Heegaard Floer homology has rank one cannot contain an essential torus. This is joint work in progress with Matt Hedden.