The odd symplectic Grassmannian IG := IG(k, 2n + 1) parametrizes k dimensional subspaces of C^2n+1 which are isotropic with respect to a general (necessarily degenerate) symplectic form. The odd symplectic group acts on IG with two orbits, and IG is itself a smooth Schubert variety in the submaximal isotropic Grassmannian IG(k, 2n + 2). We use the technique of curve neighborhoods to prove a Chevalley formula in the equivariant quantum cohomology of IG, i.e. a formula to multiply a Schubert class by the Schubert divisor class. This generalizes a formula of Pech in the case k = 2, and it gives an algorithm to calculate any quantum multiplication in the equivariant quantum cohomology ring. / Ph. D. / The thesis studies a problem in the general area of Combinatorial Algebraic Geometry. The goal of Algebraic Geometry is to study solutions to systems to polynomial equations. Such systems are ubiquitous in scientific research. We study a problem in enumerative geometry on a space called the odd symplectic Grassmannian. The problem seeks to find the number of curves which are incident to certain subspaces of the given Grassmannian. Due to subtle geometric considerations, the count is sometimes virtual, meaning that some curves need to be counted negatively. The rigorous context of such questions is that of Gromov-Witten theory, a subject with roots in physics. Our space affords a large number of symmetries, and the given counting problems translate into significant amount of combinatorial manipulations. The main result in the dissertation is a combinatorial algorithm to perform the virtual curve counting in the odd-symplectic Grassmannian.