One line of theorizing suggests considering death reminders—i.e., mortality salience (MS) inductions—unique in their effect on worldview defenses (e.g., Pyszczynski et al., 2006). Other theorizing suggests that meaning and certainty threats produce effects similar to MS and thus that these threats be considered theoretically equivalent (e.g., Proulx & Heine, 2006; McGregor, 2006). To help reconcile these discrepant perspectives, we meta-analytically examined MS effects as a function of the control condition utilized (meaning/certainty threats vs. other topics) and the length of delay between threat induction and subsequent defense. Results showed that MS and meaning/certainty threats both increased defensiveness after a short delay. But with a longer delay, MS produced even higher levels of defensiveness while meaning/certainty threats produced lower levels of defensiveness. Thus, the evidence supports a similarity between MS and meaning/certainty threat effects, but also a difference in time course that warrants their study as unique psychological threats. Copyright © 2010 John Wiley & Sons, Ltd.