I think the other suggestions assume that the selected items start at the beginning and are contiguous
This might be a little more flexible since it uses an output row counter that get incremented only when a selected list box item is written to the sheet
Dim idxListbox As Long, idxCell As Long
idxCell = 1
Sheet1.Cells(1, idxCell) = "ListBox1 Selected Items"
For idxListbox = 0 To ListBox1.ListCount - 1
If ListBox1.Selected(idxListbox) Then
idxCell = idxCell + 1
Sheet1.Cells(i, idxCell) = ListBox1.List(idxListbox)
End If
Next