| Tourney Name: | Copa Libertadores de América |
| Year: | 1978 |
| Dates: | June 27 – November 28 |
| Num Teams: | 21 |
| Associations: | 10 |
| Champion Other: |  Boca Juniors |
| Count: | 2 |
| Second Other: |  Deportivo Cali |
| Matches: | 75 |
| Goals: | 179 |
| Prevseason: | 1977 |
| Nextseason: | 1979 |
The 1978 edition of Copa Libertadores was won by Boca Juniors, of Argentina for the second straight year, after defeating Deportivo Cali of Colombia in the final. The defending champions won the two-leg final 0–4 on aggregate, with all four goals coming in the second-leg match after the first leg ended in a goalless draw.
| width=125 | Country | width=150 | Team | width=300 | Qualification method |
|---|---|---|---|---|---|
| CONMEBOL (1 berth) | Boca Juniors | 1977 Copa Libertadores champion | |||
| Argentina (2 berths) | River Plate | 1977 Metropolitano champion | |||
| Independiente | 1977 Nacional champion | ||||
(2 berths) | The Strongest | 1977 Primera División champion | |||
| Oriente Petrolero | 1977 Primera División runner-up | ||||
(2 berths) | São Paulo | 1977 Campeonato Brasileiro Série A champion | |||
| Atlético Mineiro | 1977 Campeonato Brasileiro Série A runner-up | ||||
(2 berths) | Unión Española | 1977 Primera División champion | |||
| Palestino | 1977 Liguilla Pre-Libertadores winner | ||||
(2 berths) | Junior | 1977 Campeonato Profesional champion | |||
| Deportivo Cali | 1977 Campeonato Profesional runner-up | ||||
(2 berths) | El Nacional | 1977 Campeonato Ecuatoriano champion | |||
| LDU Quito | 1977 Campeonato Ecuatoriano runner-up | ||||
(2 berths) | Cerro Porteño | 1977 Primera División champion | |||
| Libertad | 1977 Primera División runner-up | ||||
(2 berths) | Alianza Lima | 1977 Primera División champion | |||
| Sporting Cristal | 1977 Primera División runner-up | ||||
(2 berths) | Peñarol | 1977 Liguilla Pre-Libertadores winner | |||
| Danubio | 1977 Liguilla Pre-Libertadores runner-up | ||||
(2 berths) | Portuguesa | 1977 Primera División champion | |||
| Estudiantes de Mérida | 1977 Primera División runner-up | ||||
The champions and runners-up of each football association were drawn into the same group along with another football association's participating teams. Three clubs from Argentina competed as Boca Juniors was champion of the 1977 Copa Libertadores. They entered the tournament in the Semifinals.
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See main article: 1978 Copa Libertadores Finals.