Hernán D. Castro has asked this court to review an order of an Administrative Law Judge (ALJ) of the Office of Administrative Hearings (OAH), issued on June 18, 2009, denying Castro’s claim for unemployment compensation. The ALJ found that Castro’s employer, Security Assurance Management, Inc. (Security), did not terminate Castro’s employment; that both before and after October 26, 2008, Castro’s last day of work for Security, Castro had declined work offered to him by his employer; and that because Castro had left his employment voluntarily, he was not entitled to compensation. The ALJ’s order reversed an earlier decision by a claims examiner of the District of Columbia Department of Employment Services (DOES), in which the examiner held that Castro had in fact been laid off for lack of work and that he was therefore eligible to receive benefits.
Before this court, Castro first contends that the ALJ abused his discretion in declining to issue a subpoena for a proposed witness. He next asserts, in part on the basis of certain documentary evidence which was not introduced before the ALJ, which is not a part of the administrative record, but which Castro nevertheless included, without objection, in an Appendix to his brief, that the ALJ erred in finding that Castro was not terminated by Security and is therefore ineligible for unemployment compensation.
We conclude, even assuming, solely for the sake of argument, that the requested subpoena should have been issued, that any error in that regard was harmless. We also hold, for the reasons stated in the concurring opinion, that the ALJ’s finding that Security did not terminate Castro is supported by substantial evidence and that Castro’s Appendix, not being a part of the administrative record, is not properly before us. Accordingly, we affirm.1
. Castro also claims in this court that he is entitled to unemployment compensation for a two-week period, prior to his last assignment, when Security had no work for him. This *751claim was not brought to the attention of the ALJ, however, and we conclude that it has not been adequately preserved.