This study investigates some sources of variability for the growth dynamics of Lactobacillus delbrueckii, a thermophilic lactic acid bacteria species used in the manufacture of numerous cheese varieties. The dynamics were studied from the tank milk to the unmoulding of Swiss-type cheeses manufactured from clean raw milk inoculated with different thermophilic starter species. 18 cheeses with 18 different combinations of starters were manufactured in similar and controlled conditions. The cheeses were inoculated with one strain of Streptococcus thermophilus – added at a low or a high level, Lactobacillus helveticus – strain 1, 2 or not, and Lactobacillus delbrueckii – strain 1, 2 or not. Strains 1 and 2 differed by their acidifying and proteolytic potentials evaluated inmilk (high for both strains 1). The results showed a large variability of L. delbrueckii growth dynamics during cheese-making. In milk already and then all along pressing, this dynamics significantly varied according to the L. delbrueckii strain, to the inoculation level of S. thermophilus, and to both the presence/absence and the strain of L. helveticus. During the pressing of Swiss-type cheeses, the growth dynamics of L. delbrueckii were significantly influenced by the other thermophilic bacteria present, strongly suggesting that some interactions took place between L. delbrueckii and both S. thermophilus and L. helveticus. If one of them probably corresponds to the published interaction from S. thermophilus towards L. delbrueckii characterised in milk and yoghurt, the others are yet unknown. These interactions and resulting L. delbrueckii growth dynamics have been found determinant for the characteristics of the ripened cheeses. Like L. delbrueckii, growth variability for S. thermophilus and L. helveticus may generate variability in ripened cheese. This variability may be used to create or maintain some diversity within Swiss-type cheeses.