After three months of gains, the index dropped to 80.3 in July from 82.1 in June.
The index is a comparison from 1985, which was assigned the value of 100.
In July, the Conference Board's Present Situation Index rose from 68.7 to 73.6, but the Expectations Index fell from 91.1 to 84.7 in the month, the research firm said.
"Consumer Confidence fell slightly in July, precipitated by a weakening in consumers' economic and job expectations. However, confidence remains well above the levels of a year ago," said Director of Economic Indicators for the Conference Board Lynn Franco.
The Conference Board said "appraisal of current conditions continues to improve."
In the July survey that involved more than 5,000 households, 20.9 percent of respondents indicated they believe business conditions were "good," up from 19.4 percent in June.
Responses indicating a belief that business conditions were "bad" fell from 24.9 to 24.5 in the month.
The percentage of respondents indicating jobs were "plentiful," rose from 11.3 percent to 12.2 percent, while those indicating jobs were difficult held close to fell from 37.1 percent to 35.5.