Objective: The present research assessed self-reported reactions to participation in a laboratory aggression paradigm immediately postexperiment and at 1-week follow-up. Method: Three hundred nineteen men completed a competitive laboratory aggression task that involved deception and mild electric shocks that were received from, and administered to, a fictitious opponent. Participants’ aggressive ideation was assessed immediately after participation, whereas their aggressive ideation and self-reported reactions to experimental procedures were assessed approximately 1 week later. Results: Participation did not increase respondents’ self-reported likelihood of engaging in aggressive behavior after completing the aggression task or at 1-week follow-up. The percentage of participants who reported inflicted insight was extremely low (approximately 1%), and this experience was associated with little distress. At 1-week follow-up, 98% of participants reported little or no adverse effects in response to the use of deception and electric shocks. Conclusion: The likelihood of adverse consequences in response to participation in laboratory aggression research is low. Of particular importance, participation is not associated with inflicted insight or an increased likelihood of engaging in aggression following participation. Findings may assist institutional review boards and researchers in making more informed analyses of the risks and benefits of laboratory aggression research. (PsycINFO Database Record (c) 2015 APA, all rights reserved)