The class of materials in which the strength of effective electron interaction becomes approximately equal to their kinetic energy are known as being strongly correlated. Their electronic structure remains one of the biggest challenges for theory and a completely general numerical algorithm is lacking. I will present recent developments that have made it possible to obtain quantitatively correct results for a certain subclass of such systems. The effectiveness of these methods will be demonstrated by showing that one can explain the magnetic properties of both biological and condensed systems such as Fe-porphyrin of Haemoglobin, Iron-sulfur clusters of nitrogenase and cuprates such as Sr2CuO3. We will end by drawing conclusions about the role of electron correlation in Biology.