A peace walk was held and a rally in Miami Gardens. It was hosted by the Trayvon Martin Foundation. Saturday would have Martin's 19th birthday.
A spokeswoman for Martin's family said the focus of the weekend was intended to explore strategies to reduce violence.
Till, a black teen, was murdered in Mississippi in 1955, and Grant, also a black teen, was fatally shot by a police officer in Oakland in 2009.
Zimmerman was acquitted last summer of fatally shooting the unarmed Martin, who is black, in February 2012.