Cheers, I think that's what I need, but here is the code so
far, just to show you what I've been trying to do:

Option Explicit
Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
Private Const LB_FINDSTRING = &H18F

Public Sub displayFieldValues(data_in As Data, list_in As ListBox, ByVal table_in As String, ByVal field_in As Integer)
Dim RecCount As Integer
Dim Counter As Integer

data_in.Refresh
For Counter = 0 To getRecords(data_in, table_in) - 1
list_in.AddItem data_in.Recordset.Fields(field_in)
data_in.Recordset.MoveNext
Next Counter
End Sub

Public Function getRecords(data_in As Data, table_in As String) As Integer
data_in.RecordSource = table_in
With data_in.Recordset
.MoveLast
getRecords = .RecordCount
.MoveFirst
End With
End Function

So you see, I want the field_in parameter of the displayFieldValues Procedure to be a String!