E XHIBIT 10.1

A SSIGNMENT AND A SSUMPTION A GREEMENT F OR

S UPPLEMENTAL E XECUTIVE R ETIREMENT P LANS

This ASSIGNMENT AND ASSUMPTION AGREEMENT (“ Agreement ”) is made and entered into effective as of the 1 ^st day of June, 2009, by and between BUSINESS STAFFING, INC., a Delaware corporation (“ BSI ”) and KAISER VENTURES LLC, a Delaware limited liability company (“ Kaiser ”).

R ECITALS

A. BSI is currently a wholly owned subsidiary of Kaiser. BSI provides administrative services to Kaiser and other affiliated companies.

B. BSI currently maintains two supplemental executive retirement plans. The Business Staffing, Inc. Supplemental Executive Retirement Plan for which Fidelity Management and Research Company currently provides administrative services was established in 1995 (the “ Fidelity SERP ”). The assets of the Fidelity SERP are held in trust under the terms of that certain Trust Agreement dated as of December 31, 2008, between BSI and Fidelity Management Trust Company (the “ Fidelity Trust ”).

C. The Business Staffing Supplemental Deferred Compensation Plan for which Pen-Cal Administrators, Inc. currently provides administrative services was established in 1997 (the “ Pen-Cal SERP ”). The assets of the Pen-Cal SERP are held in trust under the terms of that certain Trust Agreement dated as of January 10, 2007, between Kaiser and The Charles Schwab Trust Company (the “ Schwab Trust ”). The Fidelity SERP and the Pen-Cal SERP are sometimes collectively referred to herein as the “ Plans” . The Fidelity Trust and the Schwab Trust are sometimes collectively referred to herein as the “ Trusts .”

D. The Fidelity SERP and Trust authorize entities that are part of a controlled group of corporations or non-corporate entities may become participating employers for the benefit of their employees and permit the Trust Agreement to be assigned with the consent of the parties thereto. It is the intention of this Assignment and Assumption that Kaiser adopt the Fidelity SERP and that BSI assign to Kaiser all of the rights and duties of the “Sponsor” of the Fidelity SERP and the Fidelity Trust under the terms of the SERP and Trust agreements.

E. The Schwab SERP and Trust also authorize entities that are a parent or affiliate to become par