Try

SELECT *
		FROM bm_Clients
		WHERE (CompanyKey = @CompanyKey OR @CompanyKey IS NULL)
			AND
			  (ClientKey = @ClientKey OR @ClientKey IS NULL)

>This stored proc takes 2 optional params.
>
>

>
>CREATE PROCEDURE bm_GetClients
>	@CompanyKey		INT = NULL,
>	@ClientKey		INT = NULL
>
>AS
>BEGIN
>
>	SELECT *
>		FROM bm_Clients
>		WHERE CompanyKey = ISNULL(@CompanyKey, CompanyKey) OR
>			  ClientKey = ISNULL(@ClientKey, ClientKey)
>
>END
>

>
>I want to pass either, both, or none. I'm running it like this:
>
>

>DECLARE @CompanyKey	INT
>DECLARE @ClientKey	INT
>SET @CompanyKey = 2
>SET @ClientKey = 5
>
>EXEC bm_GetClients
>EXEC bm_GetClients @ClientKey
>EXEC bm_GetClients @CompanyKey, @ClientKey 
>EXEC bm_GetClients @CompanyKey
>

>
>In all cases I'm getting back all records. If I change the OR to AND, then the second run returns no records.