July 12, 1974 was a Friday. See the Related Link below for a great website that can answer all these kinds of questions for you (only back to the year 1900 though).
The day of the week that July 12th falls on varies each year.
12th July 1966 was a Tuesday.
July 12, 1963, was a Friday.
It was a Saturday.
Sunday
20 July 1974 was a Saturday.
July 3 1974 was a Wednesday.
July 8 1974 was a Monday.
July 10 1974 was a Wednesday.
July 12th 1985 was a Friday.
Saturday.
July 11, 1974 fell on a Thursday