Liz, There are lots of reasons folks disappear from census records. If you haven't examined every single page of the area where you are SURE they were living, it's likely a transcription error or a census-taker error. Computer searches are likely to miss people under these circumstances. You'd be surprised at how mangled even simple names could be, either on the original forms or in the transcriptions of them. If other family members took in the children (for however short a time), they may be accidentally listed under the surname of the other head-of-household. Or they may just have moved from the area or been out of the country at the time the census was taken. If you haven't already tried doing so, try searching by first name and age range, and broaden the search to include other counties or even other states. I tend to find more people using this method. You could also check www.ellisisland.org to see if they show up as returning to the US in this timeframe. Many US citizens show up in the Ellis Island records when they returned from travels abroad. Finally, just to show you anything can happen ... My folks were renting an apartment in the 1960s in the upstairs of a woman's house. It was an "illegal" rental, and the owner asked them not to come to the door when the 1960 census taker came around. So, my folks will not show up anywhere on that census. Best of luck, Laura