Response bias characterized by decreases in self-reported subjective states when measured repeatedly over short time-frames is a potential concern in social science. Recent work suggests that this initial elevation bias (IEB) is pronounced among young adult students' self-reports of affect when using ambulatory methods, but it is unclear if such bias extends broadly across samples, designs, and constructs. We examined the conditions wherein reliable and robust IEB may manifest by conducting a coordinated analysis of seven ecological momentary assessment (EMA) studies with diverse lifespan samples to test the generalizability of IEB across study designs and affective constructs (momentary negative and positive affect). Overall, evidence for substantial IEB across studies was weak. No reliable evidence emerged for IEB in negative affect, with evidence for a small magnitude IEB for positive affect when comparing initial reports with reports made 1 week later, although the latter was not evident in other comparisons and was attenuated to nonsignificance when controlling for temporal factors. The magnitude and direction of IEB varied, but in mostly nonsystematic ways, as a function of study design and affective valence. Meta-analytic summary revealed consistently low combined effect sizes (Cohen's ds ranging from -.05 to .14). We found little evidence that IEB in momentary affect is sufficiently reliable, robust, or generalizable across designs and constructs to pose broad and/or serious concerns for EMA studies. Nonetheless, we recommend systematically examining the potential for IEB across study designs and constructs to help identify the conditions/contexts where IEB may or may not manifest. (PsycInfo Database Record (c) 2022 APA, all rights reserved).