APT has developed a revolutionary approach for QSAR analysis of small molecule data sets that is able to devise mathematical relationships down to atom type resolution. This approach, known as 3D-CANT (three dimensional correlation analyses) has many advantages over existing approaches. The most significant advantage of 3D-CANT is the ability to mathematically compute the contributions of each atom type in a given molecule (see figure). With this information, computational chemists can effectively determine which atom type plays the most significant role in relation to the property of the molecule. This information allows the computational scientist to rationally design a new molecule with improved properties. Unlike grid based methodologies such as CoMFA, 3D-CANT does not require super-imposable datasets, which means 3D-CANT can operate on structurally diverse molecules. Other advantages of 3D-CANT include: the ability to deal with molecules involving covalent and non-covalent interaction, molecular charges do not need to be calculated, and the models are highly predictive. In addition, a powerful and complementary software Multi-CAN, a proprietary protocol that combines the strength of structure based design and ligand based design, has also been developed for drug lead optimization.