This article will examine the history of the substantial evidence rule in Texas jurisprudence. Part II of this paper will examine some of the early cases involving the substantial evidence rule. Part III of the paper will examine more recent cases regarding the substantial evidence rule. Finally, Part IV of the paper will examine the recent Park Haven case, including the administrative agency record, and discuss the state agency's failure to demonstrate substantial evidence. In sum, this article instructs challengers of agency decisions about how to prepare for a substantial evidence review.