I will answer my own question if it is permitted. It may not be the most elegant solution. To recap, my data looked like pid choice var ... 1 1 1 ... 1 0 1 ... 2 1 0 ... 2 0 0 ... 3 0 1 ... 3 1 0 ... ... ... ... ... To successfully use PROC MI, I "rolled" the observations with the same pid into a single row, so that my input would look something like this pid choice var1 var2 ... 1 1 1 1 ... 2 1 0 0 ... 3 2 1 0 ... ... ... ... ... ... for the same data as the first table. After PROC MI, I would split the rows into the format needed to use PROC MDC. It turns out this was pretty trivial, I was just in a state of tunnel vision! ... View more