This summary was created as a companion document to the National Clearinghouse on Autism Evidence and Practice (NCAEP) systematic review article and report (see Hume et al., 2021; Steinbrenner et al., 2020; https://ncaep.fpg.unc.edu/). In that article and report, we provide supporting evidence for identified practices using studies with positive effects. We did not, however, describe practices for which studies demonstrated an absence of evidence or null effects. The objective of this document is to summarize the null findings discovered during our systematic review from 1990-2017.