When Bryce Harper was introduced as a member of the Washington Nationals, general manager Mike Rizzo said there was a chance he would play in the Arizona Fall League after the season.
As of right now, though, it appears that will not be the case. The Nationals have announced their initial list of participants in the league, and it doesn't include Harper. Via Mark Zuckerman:
The full list headed to Arizona in October...
OF Michael Burgess
RHP Adam Carr
RHP Cole Kimball
INF Stephen Lombardozzi
C Derek Norris
LHP Sammy Solis
This list isn't final, to be clear, and Rizzo did say that there's a chance Harper would be added depending on how he played in the Florida Instructional League. As of right now, though, Harper isn't on the Nationals' Arizona Fall League roster.