The purpose of the paper is to study growth in small towns. The data units are the 158 Québec towns whose population varied between 1 000 and 5 133 in 1961 and which were not included in metropolitan areas. Four growth periods have been defined (1951-1956, 1956-1961, 1961-1966 and 1966-1971) and studied by means of factor analysis using 51 variables (1961 data) depicting urban morphology, social and economic structure, local behaviour and geographical environment. The main results obtained are : 1- growth factors are different from one size group (below 2 388) to another (over 2 484) ; 2- des-pite these differences, a radio concentric structure can be distinguished which has strongly influenced the growth behaviour of the towns ; 3— growth over one period rarely constitutes in itself a component and no period is systematically correlated with the others ; 4- ultra-rapid growth seems always to be associated with the creation of new frontier towns (mainly mining towns) on the periphery ; 5— suburbanisation is a primary factor in the evolution of the smaller units ; 6- regional tertiary activities are a slow but strong factor of growth in the upper size group ; 7- the stagnation or decrease of population in the lower size group is typical outside the core area (defined by a line joining Montreal-Quebec and Sherbrooke), and 8- this same group is considerably more influenced by the local context despite the small gap between their population size : 9— finally, the main result of the study may be to illustrate the usefulness of the partition of urban units according to their size for the analysis of urban growth, and to give more precise direction for further research on the growth of small towns.