This seminar will begin with an introduction of the multidimensional construct of healthcare access, providing a well-established definition and common objectives in access measurement and inference. Different approaches will be presented, focusing on rigorous mathematical models to estimate access, including optimization and simulation under uncertainty of the model inputs. Important aspects will be covered including spatial dependence in the decision parameters of optimization models used to estimate healthcare access and Bayesian hierarchical models used to specify the sampling distributions of model inputs. The models will be illustrated for modeling access to mental healthcare in Georgia, United States.