The wine growing sector has long been deep-rooted in the Valencian Community and, even if its importance in the local economy is not so outstanding (it represents 5,2 % of all sales in the food industry of the region), it shows a remarkable importance in the society (the cooperativism represents about 770 % in the initial process of commercialization), as well as in the territory and the environment (it covers vast underprivileged and mountainous areas with scarce options to other crops).

	However, the existing imbalance between supply and demand of wine products provokes a harsh reduction of the prices in the fields. T his has of course consequences for the vineyard owners, who often see that their income is lower than production costs.

	Therefore, the main goals to be achieved in this thesis are: on the one hand, to determine the competitive position of the local wine growing sector; on the other hand, to determine the decisive factors for wine quality and its close relation with the commercial value and the differentiation of them, with the purpose of identifying those aspects which may mostly contribute to improve the competitivity of wine and, in particular the one related to factors of higher level, via price and quality.

	The competitive position of the local wine growing industry has been summarized: a) in terms of endogenous and exogenous factors that have influence on it, using the known dafo method; b) according to the decissive factors the Porterīs diamond model consists of. The competitive intensity or rivalry among the companies that form the sector has been defined using Porterīs model of the five forces.

	The conclusion of both a) and b) models shows that the competitive situation of the sector is weak, since most of the companies are unable to incorporate added value to their in bulk commercialized productions. On the other hand, the hard competition observed in the sector itself should have become the main stimulus to create a strong competitive edge. He explanation of why this did not happen has been illustrated by model of the diamond. The joint contribution of the six edges of the diamond to the achievement of competitivity is low. None of the edges is developed in a proper way, which means that we can affirm that a real diamond does not exist.

	The identification and quantification of the factors that determine the competitivity through the differentiation of prices has been carried out from the conceptual proposals of the Theory of Resources and Abilities and from the multivariante analysis of data (analysis of main components, analysis of multivariante and linear regression, and analysis of differentiation). As a consequence of previous works, it has been revealed that the three factors that mostly contribute to the differentiation of prices are, in order of importance, the following: the variety of grapes, the method of fermentation and the technological or investment effort. These three factors together can explain the variability of prices more than 60 % of the time.

	Finally, whit the object of valueing the relative importance of each of dimensions empirically obtained, a questionnaire has been handed out to managers and directors of wine cellar in order to prove the level of desviation of results above-mentioned and the subjective opinion of the above-mentioned managers. The results has been satisfactory since there is a high level of agreement on the factors that mainly contribute, as well as on those which have less importance on the differentiation of prices. This explains why the sensitizing of cellar managers is a clue dimension to the real process of differentiation of wine quality which many cellars are going through.