I have read x-data (from text files) into list1, and y-data similarly into list2:
list1 = { 0.0, 0.172, 0.266, ..}
list2 = {-5.605, -5.970, -6.505, ..}
How do I combine the two lists in order to plot points {0.0, -5.605}, {0.172, -5.970}, {0.266, -6.505},....
If you don't like Pinguin Dirk's suggestion try
Transpose[{list1,list2}]