This is a multi-center, randomized, double-blind, placebo-controlled, 2-arm, parallel group study to evaluate the efficacy and safety of ADS-5102 extended release (ER) capsules, an investigational formulation of amantadine, dosed once nightly at bedtime for the treatment of levodopa induced dyskinesia (LID) in subjects with Parkinson's disease (PD). The novel pharmacokinetic profile of ADS-5102 is expected to achieve i) maximal concentrations in the early morning through mid-day, when LID can be troublesome, and ii) lower concentrations in the evening, potentially reducing the negative impact of amantadine on sleep. This pharmacokinetic profile could enable higher doses to be tolerated with a once-nightly ER formulation than can be tolerated with an immediate-release formulation. The once-nightly dosing regimen may also provide enhanced convenience and compliance.