"I have a form with the User ID and Password fields. What is the correct syntax to find the User_ID in the PASSWORD table that was entered in on the form and again for the PASS_WORD?"

Use a DCount() function to count the number of records that match for user name AND password, this should be either 1 (match) or 0 (no match). This has the advantage of being self-contained. . .you would put this in an OnClick event on the form:

Private Sub btnOK_Click()
    If UserPasswordOK = True Then
        ' user validated. . .
    Else
        ' invalid user or password. . .
    EndIf
End Sub

Function UserPasswordOK() As Boolean
    Dim crit As String, x As Long
    If Len(Me![User ID])>0 And Len(Me![Password])>0 Then
        crit = "[User ID] = '" & Me![User ID] & "' And [Password] = '" & 
Me![Password] & "'"
        x = DCount("*","PASSWORD",crit)
        If x = 1 Then
            UserPasswordOK= True
        Else
            UserPasswordOK = False
        EndIf
    Else
    UserPasswordOK = False
End Function

This assumes that both user ID and password are strings.