Based on the ‘Inclusion Model of Environmental Concern’, we tested whether daily messaging intervention increases participants’ pro-environmental behavior (PEB). In a two (time: pre vs. post, repeated measure) × three (condition: egoistic appeals, ecological appeals, control group) experimental design, two hundred and eighteen individuals received either daily messages containing egoistic appeals for action to prevent climate change (e.g., preventing personal consequences of released diseases in melting arctic ice), ecological appeals (e.g., ecological consequences of melting glaciers), or no messages (control). PEB was assessed via self-reports and donations to an environmental organization. Neither of the appeals had an effect on the two dependent measures. Irrespective of experimental conditions, self-reported PEB was higher in the post- compared with the pre-test. Overall, the present results do not provide support for the effectiveness of a daily messaging technique. Instead, it appears that ‘being observed’ is the more effective ‘intervention’. Implications for how to foster PEB are discussed.