This has been a topic of much controversy since the invention of technical analysis, and it remains a very heated debate. A selffulfilling prophecy is an event that is caused only by the preceding prediction or expectation that it was going to occur.
On the one hand, the tools used in technical analysis  such as support and resistance, trendlines, major daily moving averages and other types of indicators  do seem to have predictive qualities. Often the price of an asset does move in the direction foretold by these indicators.
However, those who see technical analysis as a selffulfilling prophecy argue that these indicators are "right" only because extremely large numbers of people base trading decisions on these same indicators, thereby using the same information to take their positions, and, in turn, pushing the price in the predicted direction. Others argue that technical indicators can predict future price movements because the basic tenets of technical analysis, on which the design of these indicators is based, are valid and provide real insight into the market and the intrinsic forces that move it.
However, both sides of the debate may be right to some extent. It is true that common signals generated by technical analysis can be self fulfilling and push the price of a security higher or lower, reinforcing the strength of the signal. That said, it's likely this may last only for a short time. Because the goals of participating investors and traders are different and there are hundreds of indicators informing these market players not to mention fundamental forces that drive prices  it becomes nearly impossible for technical analysis to be self fulfilling in the long run.
For example, many technical traders will place a stoploss order below the 200day moving average of a certain company. If a large number of traders have done so and the stock reaches this price, there will be a large number of sell orders, which will push the stock down, confirming the movement traders anticipated. Then, other traders will see the price decrease and also sell their positions, reinforcing the strength of the trend. This shortterm selling pressure can be considered selffulfilling, but it will have little bearing on where the asset's price will be weeks or months from now. In sum, if enough people use the same signals, they could cause the movement foretold by the signal, but over the long run this sole group of traders cannot drive price.
To learn more about technical analysis see the tutorial The Basics Of Technical Analysis and Analyzing Chart Patterns.

What types of data are necessary to make a technical analysis?
Understand what technical analysis is, the basic theory behind employing it and what data inputs are needed to conduct it. Read Answer >> 
How do I start using technical analysis?
Technical analysis is a method of analyzing securities by evaluating current and historical price and/or volume activity. ... Read Answer >> 
I keep hearing about the 50day, 100day and 200day moving averages. What do they ...
Whether you are using the 50day, 100day or 200day moving average, the method of calculation and the manner in which the ... Read Answer >> 
How do technical analysts predict bull markets?
Dive into the methods and assumptions of technical analysis, and see how analysts go about trying to predict a bull market ... Read Answer >> 
How legitimate are companies that advertise debt consolidation for all my credit ...
Learn about how fundamental analysis ratios can be combined with quantitative stock screening methods and how technical indicators ... Read Answer >> 
Why does the efficient market hypothesis state that technical analysis is bunk?
Learn about why there are strong conceptual differences between the efficient market hypothesis and technical analysis about ... Read Answer >>

Markets
Debunking 8 Myths About Technical Analysis
Investopedia exposes a few common myths about technical analysis. 
Trading
Technical Vs. Fundamental Investing  Friends Or Foes?
Making money in the stock market has been likened to gambling by some, but experienced investors who do their homework usually profit by doing market analysis. However, even experienced investors ... 
Trading
Technical Analysis: The Basic Assumptions
By Cory Janssen, Chad Langager and Casey MurphyWhat Is Technical Analysis? Technical analysis is a method of evaluating securities by analyzing the statistics generated by market activity, such ... 
Trading
Introduction to Types of Trading: Technical Traders
Learn about the different traders and explore in detail the broader approach that looks to the past to predict the future. 
Trading
Profit Without Predicting The Market
Traders who try to predict the future can actually harm their trading options. 
Managing Wealth
Use Price Action Trading Strategy for Results
Bored by the fixed rules of technical and fundamental analysis? Price action trading allows you to customize your own trading strategy. 
Markets
Fundamentals And Technicals: Together At Last
It's a big mistake for a fundamental investor to ignore technical analysis. Find out how to become chart smart. 
Trading
Trading With Support And Resistance
Learn more about these two technical analysis levels and how traders use them as signals to buy or sell a security. 
Personal Finance
Exploring Oscillators and Indicators
Find out how to use these technical analysis building blocks. 
Trading
How To Build A Trading Indicator
Wondering how people like Elliott and Gann built their famous trading tools? Learn the basics of constructing an indicator.

Technical Analysis
A method of evaluating securities by analyzing statistics generated ... 
Stock Analysis
Stock analysis is a term that refers to the evaluation of a particular ... 
Indicator
Indicators are statistics used to measure current conditions ... 
Technical Indicator
Any class of metrics whose value is derived from generic price ... 
Fakeout
A term used in technical analysis to refer to a situation in ... 
Confirmation
The use of an additional indicator or indicators to substantiate ...