The solubility parameters of a broad spectrum of solvents and chemicals are calculated from vapor pressure data using an expression derived from the relationship of Haggenmacher. In the case of high boiling liquids, the available vapor pressure data are found to be unreliable when extrapolated to room temperature and an alternate method of calculation is proposed. A structure correlation is made using the method of Small and new values of the molar cohesion constants are developed. The problem of associations of certain molecular species is discussed and the concept of chameleonic character introduced as a qualitative explanation.