This paper describes the results of an online field experiment where we designed and analyzed the effects of a goal-setting tracker in an online citizen science project Floating Forest. The design of our tracker was influenced by psychology theories of anchoring and goal-setting. Our results of our experiment revealed: (1) setting goals increases annotations in a session; (2) numeric anchors influence goals; and (3) participants in the treatment who saw a prompt but did not set a goal, contributed more annotations than the participants in the control group. Our research shows how goal-setting and anchoring combine to increase work in online communities. Author Keywords citizen science; experiments; goal-setting ACM Classification Keywords H.5.m [Information interfaces and presentation (e.g., HCI)]: Experimentation