A major goal of nuclear theory is to explain the wealth of data and peculiarities exhibited
by nuclear systems in a fully microscopic approach. In such an approach, which we refer
to as the basic model of nuclear theory, the nucleons interact with each other via twoand
many-body e ective interactions, and with external electroweak probes via e ective
current operators. These e ective interactions and currents are the main inputs to ab-initio
methods that are aimed at solving the many-body Schrodinger equation associated with the
nuclear system under consideration. In this talk, I will review recent progress in Quantum
Monte Carlo calculations of low-lying spectra and electroweak properties of light nuclei and
nucleonic matter equation of state. Emphasis will be placed on calculations based on chiral
e ective  eld theory approach.