Two of the fields that I have on a form are 'Call Type' and 'Please Specify'.
'Call Type' is a combo box with multiple values in. One of these values is 'Other'.
What I am trying to achieve is to have the 'Please Specify' field to become required , ie, input needed, IF the call type value chosen is Other.
Any help out there ?

In the After Update event of your Combo box you can use code like this:

If Me![ComboBoxName] = "Other" Then
Me![PleaseSpecify].SetFocus
End If

In your PleaseSpecify text box put code to insure that the user inputs data.

Note: If "Other" in your Combo box is not the bound column then you will need to refer to the correct column in the code above.