A great need exists for knowledge of effectiveness and limits of suitability of brief interventions in suicide prevention. Numerous intervention studies have already been conducted to investigate their effectiveness in reducing risk of suicide reattempts. However, it is important for the field to be aware of the fundamental importance of study designs, particularly choice of comparison groups for observed success on preventive interventions, as different study designs are needed for different research questions. Information on effectiveness of interventions is always obtained by comparing them to something else. Most brief intervention studies have compared outcomes of subjects who have or have not received an intervention, with subjects concurrently receiving their usual treatment (TAU). Such studies inform about the overall added benefits of interventions, including both specific and unspecific effects. However, even when found effective, whether effectiveness exceeds that of any unspecific other added intervention remains unknown. Alternatively, in order to demonstrate specific superiority of an intervention, studies may compare an active intervention to an unspecific comparison intervention. The Attempted Suicide Short Intervention Program (ASSIP) is a brief, three-visit psychotherapeutic intervention including a videotaped narrative interview and creation of a safety plan. It was found remarkably effective in reducing repeat suicide attempts in the pivotal Swiss study, which compared the ASSIP with TAU and found an 80% reduction in repeated attempts. In contrast, we compared the effectiveness of ASSIP to crisis counselling (CC) in a randomized clinical trial to examine whether it is specifically superior to a nonspecific other intervention. Consenting adult patients receiving treatment for a suicide attempt in Helsinki City general hospital emergency rooms in 2016-2017 (n = 239) were Zelen-randomized to either the ASSIP or the CC. One and two years after baseline, information on outcome was collected via telephone and from medical and psychiatric records. Of patients who initiated ASSIP (n = 89) or CC (n = 72), 73 (82%) completed ASSIP and 58 (81%) CC. The proportion of patients who attempted suicide during the two-year follow-up did not differ significantly between ASSIP and CC (29.2% vs. 35.2%). Our study put the ASSIP to a more stringent test than most other studies of suicide brief interventions, as it was designed to demonstrate specific effectiveness rather than effectiveness over TAU. However, our findings demonstrate the need to refine understanding of factors that could result in effectiveness of interventions exceeding that of common factors in brief therapies.