Mar. 01, 2019

Russell Investment Company: Classes A, C, C1, E, M, P, R6, S, T and Y

RUSSELL INVESTMENT COMPANY

Supplement dated March 14, 2019 to

PROSPECTUS DATED March 1, 2019

U.S. SMALL CAP EQUITY FUND RISK/RETURN SUMMARY:

(i) The following replaces the second paragraph in the sub-section entitled “Principal Investment Strategies of the Fund” in the Risk/Return Summary section for the U.S. Small Cap Equity Fund in the Prospectus listed above:

Russell Investment Management, LLC (“RIM”) provides or oversees the provision of all investment advisory and portfolio management services for the Fund. The Fund is advised by RIM and multiple money managers unaffiliated with RIM pursuant to a multi-style (e.g., growth, value, market-oriented, defensive and/or dynamic) and multi-manager approach. The Fund employs discretionary and non-discretionary money managers. The Fund’s discretionary money managers select the individual portfolio instruments for the assets assigned to them. The Fund’s non-discretionary money managers provide a model portfolio to RIM representing their investment recommendations, based upon which RIM purchases and sells securities for the Fund. RIM manages Fund assets not allocated to money manager strategies and utilizes quantitative and/or rules-based processes and qualitative analysis to assess Fund characteristics and invest in securities and instruments which provide the desired exposures. RIM may use strategies based on indexes. RIM also manages the portion of Fund assets for which the Fund’s non-discretionary money managers provide model portfolios and the Fund’s cash balances. The Fund usually, but not always, pursues a strategy to be fully invested by exposing all or a portion of its cash to the performance of appropriate markets by purchasing equity securities and/or derivatives, which typically include index futures contracts.

(ii) The following information is added to the sub-section entitled “Principal Risks of Investing in the Fund” in the Risk/Return Summary section for the U.S. Small Cap Equity Fund:

• Non-Discretionary Implementation Risk. With respect to the portion of the Fund that is managed pursuant to model portfolios provided by non-discretionary money managers, it is expected that trades will be effected on a periodic basis and therefore less frequently than would typically be the case if discretionary money managers were employed. Given that values of investments change with market conditions, this could cause the Fund’s return to be lower than if the Fund employed discretionary money managers with respect to that portion of its portfolio.