Preliminary research indicates that applying this technique to foot weakness after stroke is safe and may improve walking function. Hence, this warrants further investigation to: 1. determine if BCI-FES therapy can provide lasting gains in walking in chronic stroke patients; 2. determine what factors influence BCI-FES therapy; and 3. explicitly elucidate the underlying neural repair mechanisms. First, a Phase II clinical trial in patients with foot drop due to chronic stroke will compare the effect of BCIFES dorsiflexion therapy to that of dose- and intensity-matched standard physical therapy (Aim 1). Comparing the improvement in walking speed and other secondary outcome measures between the two groups will test if BCI-FES therapy provides functional and neurological gains beyond those of standard physical therapy. The relationship between the patient baseline characteristics (walking speed, ankle function, stimulated muscle responses, brain wave features, sensation) and the outcomes will determine what features influence responsiveness to BCI-FES dorsiflexion therapy (Aim 2). Finally, the underlying mechanism driving the improvements of BCI-FES will be studied (Aim 3). Determining that BCI-FES therapy can provide improvements beyond that of standard therapy may lead to a new treatment for stroke patients. The underlying mechanism can inform the design of future physical therapy techniques or improve current ones. Finally, BCI-FES therapy may ultimately become a novel form of physical therapy to reduce post-stroke disability, and in turn reduce the public health burden of stroke.