RestAdapter ra = new RestAdapter.Builder() .setServer("http://api.stackexchange.com/2.1") .build(); ISites sites = ra.create(ISites.class); ra.getAllSites("", new Callback<CommonSEWrapper<Site>>(){ @Override public void failure(RetrofitError argRetrofitError){ } @Override public void success(CommonSEWrapper<Site> sites, Response response){ // sites is filled in, just like magic! } });