The ab initio No-Core Shell Model (NCSM) begins with an intrinsic Hamiltonian for all nucleons in the nucleus. Realistic two-nucleon and tri-nucleon interactions are incorporated such as those recently developed from effective-field theory and chiral perturbation theory. We then derive a finite basis-space dependent Hermitian effective Hamiltonian that conserves all the symmetries of the initial Hamiltonian. The resulting finite Hamiltonian matrix problem is solved by diagonalization on parallel computers. Applications range from light nuclei to multiquark systems and, recently, to quantum-field theory including systems with bosons. We present this approach with a sample of recent results.