My project involves designing mathematical models that will help understand drug resistance evolution. The current focus is on parasitic worms or helminths. Helminth infections in humans are neglected tropical diseases, that are targeted by mass drug administration programs. This periodic treatment raises the concern of resistance emerging as it has done repeatedly in livestock infecting helminths. Whereas there are a vast amount of models simulating drug resistance evolution in bacteria, fewer exist for fungi and even less for helminths. The focus in helminth models has been more on the epidemiology, however in various places, drug efficacy seems to be declining for all major helminth groups. Mathematical models that include population genetical approached linked with pharmacodynamics can provide insights into processes associated with faster and slower emergence and spread of drug resistance.