Secondary abilities are more specialized versions of Primary abilities. In this game they cost the same as Primary abilities, BUT when used the rolls are made with a -2 to the difficulty. ST's must clear the Secondary ability when initially purchased. No Secondary Ability can be higher than its Primary Ability counterpart. For example if you want the Secondary Ability of Toxicology then you firstly need the Primary Ability of Science. If you have any problems figuring out what Secondary Ability is grouped form what Primary Ability please talk to an ST.