The growing use of non-invasive brain stimulation in clinical applications reflects its capabilities to transiently modulate cortical excitability, motor and cognitive functions in ways not possible with other techniques. Neurological disorders represent the consequence of dynamic plastic interactions in distributed neural networks; in this context brain stimulation allows enhancement of adaptive processes and prevention of potential maladaptive ones. The purpose of this chapter is to provide an update on the field of transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) as non-invasive stimulation techniques that are currently applicable to improve motor and cognitive functions in patients suffering from stroke, Alzheimer’s, and Parkinson’s disease. Cortical stimulation may activate, inhibit, or otherwise interfere with the activity of various cortico-subcortical networks, depending on the location of stimulation, stimulus intensity and frequency, current polarity, and the configuration of the induced electric field. Interestingly, functional and clinical effects occur not only during but also beyond the time of stimulation, and might be related to processes of synaptic plasticity. In brief, the present chapter will provide a present day’s framework of the application of non-invasive brain stimulation targeted to selected examples of common neurological diseases, and suggestions to guide future efforts