public void Test()
{
    object[] obj = new object[5];

    obj[0] = "テストメッセージ1";
    obj[1] = 2;
    obj[2] = DateTime.Now;
    obj[3] = false;
    obj[4] = "テストメッセージ2";

    Thread thread = new Thread(new ParameterizedThreadStart(TestProc));
    thread.Start(obj);
}

public void TestProc(object args)
{
    // 引数の展開します。
    object[] argsTmp = (object[])args;
    for (int i = 0; i < argsTmp.Length; i++)
    {
        Console.WriteLine((string)argsTmp[i].ToString());
    }
}