Canon 346. §1 The synod of Bishops meeting in ordinary general assembly is comprised, for the most part, of Bishops elected for each assembly by the Episcopal Conferences, in accordance with the norms of the special law of the synod. Other members are designated according to the same law; others are directly appointed by the Roman Pontiff. Added to these are some members of clerical religious institutes, elected in accordance with the same special law.
[NB see Authentic Interpretation of canon 346 §1, 10.X.1991]

§2 The synod of Bishops meeting in extraordinary general assembly for the purpose of dealing with matters which require speedy resolution, is comprised for the most part, of Bishops who, by reason of the office they hold, are designated by the special law of the synod; others are appointed directly by the Roman Pontiff. Added to these are some members of clerical religious institutes, elected in accordance with the same law.

§3 The synod of Bishops which meets in special assembly is comprised of members chosen principally from those regions for which the synod was convened, in accordance with the special law by which the synod is governed.

§1. Synodus Episcoporum quae in coetum generalem ordinarium congregatur, constat sodalibus quorum plerique sunt Episcopi, electi pro singulis coetibus ab Episcoporum conferentiis secundum rationem iure peculiari synodi determinatam; alii vi eiusdem iuris deputantur; alii a Romano Pontifice directe nominantur; quibus accedunt aliqui sodales institutorum religiosorum clericalium, qui ad normam eiusdem iuris peculiaris eliguntur.

§2. Synodus Episcoporum in coetum generalem extraordinarium congregata ad negotia tractanda quae expeditam requirant definitionem, constat sodalibus quorum plerique, Episcopi, a iure peculiari synodi deputantur ratione officii quod adimplent, alii vero a Romano Pontifice directe nominantur; quibus accedunt aliqui sodales institutorum religiosorum clericalium ad normam eiusdem iuris electi.

§3. Synodus Episcoporum, quae in coetum specialem congregatur, constat sodalibus delectis praecipue ex iis regionibus pro quibus convocata est, ad normam iuris peculiaris, quo synodus regitur.