This paper describes four human error incidents in chemical process plants which I have personally observed, and discusses specific lessons from each of them. As often stated by Trevor Kletz, people respond to stories and examples, and hopefully these incidents will be useful in preventing similar incidents in the future. Fortunately none of the incidents resulted in serious safety consequences, although all cost some money and productivity. And, under other circumstances, similar errors in a more hazardous operation could have had serious safety consequences.