Reply To: Portfolio on 3 columns

In your css file, take a look for something like this around line 1722 –

#content .portfolio {
    float: left;
    margin: 0 2% 40px 0 !important;
    overflow: hidden;
    padding: 0;
    width: 23%;
}

and change the width to around 30% or so until you get the size you want.